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Biomedical subjects

K Fox

Publications and source records attributed to K Fox.

At least 37 records · Page 2Linked to original sources
PubMed1994

The influence of young age on outcome in early stage breast cancer.

PURPOSE: To assess the impact of young age on outcome in women with early stage breast cancer undergoing conservative surgery and radiation. METHODS AND MATERIALS: Between 1981 and 1991, 980 patients with Stage I and II breast cancer underwent excisional biopsy, axillary dissection, and radiation. The median follow-up was 4.6 years, with a range of 1 month to 11 years. The patients were divided into three groups, based on age at the time of diagnosis: (a) age < or = 35 years--64 patients, (b) age 36-50 years--363 patients, and (c) age > 50 years--553 patients. The comparability of the groups was assessed in terms of clinical factors (tumor size and race), histopathologic factors (histologic subtype, final resection margin, estrogen and progesterone receptor status, pathologic nodal status), and treatment related factors (reexcision, median total dose to the primary, region(s) treated with radiation, and the use of adjuvant systemic chemotherapy and/or tamoxifen). Outcome was evaluated for overall, relapse-free, and cause-specific survival and patterns of first failure (breast, regional nodes, and distant metastasis). RESULTS: There were no significant differences among the three groups in terms of race, clinical tumor size, pathology of the primary tumor, pathologic nodal status, final margin of resection, progesterone receptor status, median total dose to the primary tumor, or the regions treated. However, younger women were significantly more likely to have estrogen receptor negative tumors, undergo reexcision, and receive adjuvant systemic chemotherapy without tamoxifen. Younger women were found to have a statistically significantly decreased 8-year actuarial relapse-free survival (53% vs. 67% vs. 74%, p = 0.009), cause-specific survival (73% vs. 84% vs. 90%, p = 0.02), freedom from distant metastasis (76% vs. 75% vs. 83%, p = 0.02), and a significantly increased risk of breast recurrence (24% vs. 14% vs. 12%, p = 0.001), and regional node recurrence (7% vs. 1% vs. 1%, p = 0.0002). The patients were further divided on the basis of their pathologic nodal status. There were no statistically significant differences among the three age groups for axillary node-positive patients for overall survival (75% vs. 80% vs. 74%), relapse-free survival (73% vs. 73% vs. 62%), cause-specific survival (76% vs. 85% vs. 80%), and freedom from distant metastasis (75% vs. 75% vs. 72%), or breast recurrence (0% vs. 9% vs. 6%). The findings were identical when the analysis was restricted to node-positive patients who received chemotherapy. However, for axillary node-negative women, young age was associated with a statistically significant decreased overall survival (71% vs. 83% vs. 92%), relapse-free survival (51% vs. 65% vs. 76%), cause-specific survival (71% vs. 86% vs. 93%), freedom from distant metastasis (77% vs. 76% vs. 88%), and a statistically significant increased risk of breast recurrence (40% vs. 16% vs. 13%), and regional node recurrence (3% vs. 1% vs. 0%). The risk of a breast recurrence in axillary node-negative young women was decreased by the addition of adjuvant systemic chemotherapy but not by the use of reexcision. CONCLUSIONS: The present analysis demonstrates that young women with early stage breast cancer do significantly worse when compared to older women in terms of relapse-free survival, cause-specific survival, distant metastasis and breast and regional node recurrence. However, the adverse effect of young age on outcome appears to be limited to the node-negative patients. These findings suggest that node-negative early stage breast cancer in young women is a more aggressive disease, with an increased risk for all patterns of failure and a decreased survival.

Adult↗
PubMed1994

Kinetics of bioconcentration and clearance of 28 polychlorinated biphenyl congeners in zebrafish (Brachydanio rerio).

Bioconcentration experiments were performed on 28 polychlorinated biphenyl (PCB) congeners with NCl = 2 to NCl = 10, evaluating them simultaneously. Bioconcentration factors (BCFs) were calculated from the uptake rate constant (k1) and the clearance rate constant (k2) as BCF = k1/k2. BCFs on a wet weight basis ranged from 7710 to 940,000. They were correlated with octanol-water partition coefficients (P). The curvilinear relationship between log BCF and log P based upon data covering the log P range 5.06 to 8.18. About a log P of 7.38, a range of "optimal lipophilicity," results in highest BCFs for PCBs, above which the degree of bioconcentration decreases.

Animals↗
PubMed1994

Nitrates in silent ischemia.

In recent years it has become clear that episodes of transient myocardial ischemia commonly occur in patients with coronary artery disease in the absence of chest pain or angina equivalent. These episodes of "silent myocardial ischemia" are particularly well documented during continuous ambulatory electrocardiographic monitoring in daily life. Evidence suggests that these episodes represent true ischemia, and appear to be a marker of unfavorable outcome. While the pathophysiology is not completely understood, it appears as though the mechanisms of angina and silent ischemia are the same. Both forms of ischemia respond to conventional antianginal medication. While long-acting nitrates are effective in reducing or preventing myocardial ischemia, because of their propensity to cause tolerance they should be used intermittently and in association with either beta-blockers or calcium antagonists. Nitrates are safe and comparatively inexpensive, and will continue to play an important role in the treatment and prevention of angina. However, in the light of current knowledge, there is no specific indication for the treatment of silent ischemia by nitrates.

Administration, Cutaneous↗
PubMed1994

Comparison of the effect of heparin and aspirin versus aspirin alone on transient myocardial ischemia and in-hospital prognosis in patients with unstable angina.

OBJECTIVES: This study compared the effects of heparin and aspirin versus aspirin alone on transient myocardial ischemia and in-hospital prognosis in patients with unstable angina. BACKGROUND: Transient myocardial ischemia occurring in patients with unstable angina is associated with an adverse prognosis. Heparin and aspirin are two drugs used frequently in the treatment of this condition, but the effect of combination therapy versus aspirin alone on transient myocardial ischemia is unknown. METHODS: Two hundred eighty-five consecutive patients with unstable angina were randomized to receive either intravenous heparin plus oral aspirin (150 mg once daily) (Group H + A) or aspirin alone (Group A). Patients also received a beta-adrenergic blocking agent, diltiazem and intravenous nitrates. ST segment monitoring was performed for the 1st 48 h of treatment. Patients were followed up for the duration of their in-hospital stay. RESULTS: One hundred fifty-four patients (30 women, mean [+/- SEM] age 58.3 +/- 0.8 years) received heparin and aspirin (Group H + A), and 131 patients (26 women, mean age 60.6 +/- 0.8 years) received aspirin only (Group A). ST segment monitoring (11,622 h) yielded 244 episodes of transient myocardial ischemia of a total duration of 7,819 min. There were no significant differences between the two treatment arms in the number of patients with transient myocardial ischemia (27 [18%] in Group H + A vs. 31 [24%] in Group A), number of episodes (96 in Group H + A vs. 148 in Group A) or total duration of transient myocardial ischemia (2,911 min in Group H + A vs. 4,908 min in Group A). The incidence of in-hospital myocardial infarction or death was significantly higher in patients with transient myocardial ischemia (53% vs. 22%, p < 0.0001). Five of the six deaths occurred in patients with transient myocardial ischemia. Event-free survival from myocardial infarction or death was similar in both treatment groups. Preadmission therapy with aspirin was associated with a lower in-hospital infarction rate (19% vs. 34%, p = 0.01). CONCLUSIONS: The presence of transient myocardial ischemia in patients with unstable angina is associated with a significantly higher incidence of myocardial infarction or death in hospital. Combined therapy with heparin and aspirin compared with aspirin alone makes no difference in the development of these events, nor does it reduce the development of transient myocardial ischemia.

Adult↗
PubMed1994

Critical period control in sensory cortex.

The search continues for factors whose regulation during development accounts for the end of the critical period for experience-dependent cortical plasticity. Recent studies suggest that NMDA receptors and neurotrophins may be involved either individually or in concert. NMDA receptor subunits are developmentally regulated in a way that affects the kinetic properties of the NMDA receptor. The expression of mRNAs for neurotrophins and their receptors is regulated by developmental factors and by neuronal activity, and exogenous neurotrophins block critical period plasticity in the visual cortex.

Animals↗
PubMed1994

Gender differences in adult health: an international comparison.

This article uses data from the United States, Jamaica, Malaysia, and Bangladesh to explore gender differences in adult health. The results show that women fare worse than men across a variety of self-reported health measures in all four countries studies. These health status disparities between men and women persist even after appropriate corrections are made for the impact of (a) differential mortality selection by gender and (b) sociodemographic factors. Data from Jamaica indicate that gender disparities in adult health arise early and persist throughout the life cycle, with different age profiles for different measures.

Adolescent↗
PubMed1994

The effects of intracoronary substance P and acetylcholine on coronary blood flow in patients with idiopathic dilated cardiomyopathy.

Attenuation of the increase in blood flow caused by acetylcholine in the peripheral vasculature and coronary circulation of patients with heart failure has been interpreted as an impairment of endothelium-dependent vasodilation. The aim of this study was to compare in man the effects of acetylcholine, which also has endothelium-independent actions, with substance P, which appears to be a pure endothelium-dependent vasodilator, on epicardial and resistance coronary arteries in patients with idiopathic dilated cardiomyopathy. The effects of intracoronary acetylcholine (10(-7) M and 10(-6) M) and substance P (5, 10 and 25 pmol.min-1) on epicardial coronary artery diameter and coronary blood flow velocity were measured with an intracoronary Doppler flow probe and quantitative coronary angiography in 11 patients with idiopathic dilated cardiomyopathy and 10 control subjects. Epicardial coronary artery diameter did not change with acetylcholine but increased significantly with substance P in both groups (cardiomyopathy patients: 3.3 +/- 0.2 mm (mean +/- SEM) at baseline vs 3.9 +/- 0.2 mm with substance P25 pmol.min-1, P < 0.01; controls: 3.1 +/- 0.2 mm at baseline vs 3.9 +/- 0.3 mm with substance P25 pmol.min-1, P < 0.05). Coronary flow ratios with acetylcholine were lower in cardiomyopathy patients (10(-7) M: 1.4 +/- 0.1 vs 2.3 +/- 0.4, P = 0.05; 10(-6) M: 1.8 +/- 0.2 vs 3.2 +/- 0.5, P = 0.05 vs controls).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Serum lactogens possessed normal bioactivity in patients with lactation insufficiency.

OBJECTIVE: Insufficient breast milk is the most common reason for premature termination of breast-feeding. The causes of lactation insufficiency are usually multifactorial; in a small percentage of cases it is due to primary lactation failure of unknown origin. The aim of this study was to investigate whether lactation insufficiency of unknown origin could be caused by serum lactogens that had reduced biological activity. DESIGN: Women with lactation insufficiency of unknown origin and normal lactating controls were subjected to a standardized breast-feeding test for assessment of milk production. Thirty minutes later, serum samples were obtained for determination of total lactogen bioactivity, using an in-vitro bioassay, and levels of prolactin (PRL) and growth hormone (GH) using radioimmunoassay (RIA). PATIENTS: Twelve lactating mothers with a clinical diagnosis of lactation insufficiency of unknown origin were compared with 12 matched mothers with normal lactation. MEASUREMENTS: The Nb2 lymphoma cell bioassay was used to measure total lactogen bioactivity in sera. Conventional RIA kits were used to estimate serum PRL and GH concentrations. RESULTS: Mean milk yield on standardized test feed was 21.6 ml for patients and 146.5 ml for controls. In both patient and control groups the total serum lactogen bioactivity ranged from about 150 to 5000 mIU/l, while the serum RIA (PRL+GH) levels ranged from about 350 to over 7000 mIU/l. There was no evidence of lactogens with reduced bioactivity in the patients' sera. CONCLUSION: Lactation insufficiency in the women studied cannot be explained by serum lactogens that possess unusually low bioactivity.

Biological Assay↗
PubMed1994

Children's task and ego goal profiles in sport.

The purpose of this study was to examine the combined effects of task and ego goal orientations on children's sport motivation. Participants were 115 boys and 116 girls (mean age = 11.12 yrs). Unlike previous research, where the correlates of the two orientations have been examined separately, this study examined the motivational consequences of different task and ego combinations. Four groups were created based on mean splits on the task and ego scales of the Task and Ego Orientation in Sport Questionnaire. These were low task/low ego, low task/high ego, high task/low ego, and high task/high ego. The hi/hi group emerged as the most motivated and the lo/lo group least motivated in measures of sport enjoyment and perceived sport competence. The lo/lo group, made up primarily of girls, appear to be at high risk for non-participation in sport. Children dominated by a task orientation were more motivated than those dominated by an ego orientation. A similar pattern emerged whether children were in the lower or upper third of the perceived sport competence distribution. A high task orientation appears to provide the vital element for sport motivation. The addition of ego involvement to task involvement may enhance sport enjoyment and does not appear to be motivationally detrimental. Task and ego profile analysis seems to offer important insight into the achievement motivation of children of this age.

Achievement↗
PubMed1994

Perceived locus of causality, goal orientations, and perceived competence in school physical education classes.

Ryan & Connell (1989) have demonstrated that different types of behavioural regulation can be located on a continuum of perceived autonomy or perceived locus of causality. The present study applied their formulation in the context of school physical education (PE) and examined the relationships of perceived autonomy, perceived competence and goal orientations with intrinsic interest across two PE activities. School students aged 12-14 years (N = 85) completed an adapted version of the Self-Regulation Questionnaire (Ryan & Connell, 1989) and measures of perceived competence and intrinsic interest separately for two PE activities. They also completed the British version of the Task and Ego Orientation in Sport Questionnaire (Duda, Fox, Biddle & Armstrong, 1992). Students appeared to be differentially motivated for the two activities due to different perceptions of autonomy. Structural equation modelling analysis showed that perceived autonomy and task orientation had direct effects on intrinsic interest for both the activities. Perceived competence, however, was positively associated with intrinsic interest only for one of the activities. The implications of the results for the practice of physical education are discussed.

Achievement↗
PubMed1994

The cortical component of experience-dependent synaptic plasticity in the rat barrel cortex.

Rats were raised with altered tactile experience from P0 by removing all but one vibrissa (D1) from one side of the face (D1-spared animals). This procedure (univibrissa rearing) has previously been shown to cause neurons in cortical barrels surrounding D1 to develop greater than normal responses to D1 vibrissa stimulation and smaller than normal responses to principal vibrissa stimulation (Fox, 1992). In this study, it was found that the potentiated D1 responses could be attenuated by acute microlesions placed in the D1 barrel, while principal vibrissa responses were unchanged or even slightly elevated for the same cases. The ratio of the average D1 to principal vibrissa response was approximately proportional to the volume of tissue damaged in the D1 barrel. This result implies that the synaptic plasticity seen in cortex of D1-spared animals is due to synaptic changes that take place within the barrel cortex rather than to relay of changes occurring at a subcortical level. In addition, lesions aimed at the septum between D1 and an adjacent barrel almost completely abolished responses to D1 stimulation in that barrel, including short-latency responses (5-10 msec). Only neurons severed horizontally from D1 were affected. Neurons that maintained a connection with the D1 barrel via a bridge of septal tissue preserved their usual elevated levels of response to D1 stimulation and their aberrant short-latency responses. This result implies that pathways radiating out from the D1 barrel/column, and connecting neurons in the D1 barrel to cells in surrounding barrels, undergo synaptic plasticity induced by univibrissa rearing.

Animals↗
PubMed1994

Quality of care in public and private primary health care facilities: structural comparisons in Jamaica.

This article examines the quality of care provided by Jamaican primary health care clinics by comparing various structural quality indexes derived from a nationwide 1990 survey of 366 public clinics and 189 private clinics. This comparison points up important differences in the quality of care being provided by public versus private and urban versus rural facilities that might not have been anticipated. Among other things, the study found that the public clinics provided better prenatal diagnosis and counseling and more family planning services than the private clinics. However, the private clinics tended to be better condition, better equipped and supplied, and better able to provide certain laboratory test results in a timely manner. Comparison of urban and rural public clinics indicated that the urban clinics were somewhat better provisioned with equipment, supplies, and pharmaceuticals. However, the rural clinics appeared to be in better repair. Comparison of basic and higher-level public clinics showed the basic clinics to be in better condition and more fully staffed than the higher-level clinics while having similar perinatal diagnostic capabilities. However, the higher-level public clinics tended to have an overall profile more resembling that of the private clinics, being better equipped and supplied than the basic clinics. While structural measures of quality such as those employed here tend to poorly estimate health outcomes, they do serve as good indicators of access to services where resources are severely constrained. For policy-makers, the results presented here could prove useful in guiding concrete interventions, summarizing the structural elements of health care quality at different types of facilities, and providing a method for less costly evaluation of programs designed to improve services at primary health care clinics.

Ambulatory Care Facilities↗
PubMed1993

Postsynaptic control of plasticity in developing somatosensory cortex.

The rearrangement of synaptic connections during normal and deprived development is though to be controlled by correlations in afferent impulse activity. A favoured model is based on post-synaptic detection of synchronously active afferents; synapses are stabilized when pre- and postsynaptic activity is correlated and weakened or eliminated when their activity is uncorrelated. Most evidence for this model comes from demonstrations that correlated afferent input is necessary for the segregation of eye-dominant inputs in the developing vertebrate visual system and that critical period plasticity of ocular dominance columns in cat visual cortex is disrupted by blockade of postsynaptic transmission. We tested whether the developmental plasticity of somatosensory columns, known as 'barrels', in rodent primary somatosensory cortex (S1) is similar to that of ocular dominance columns. We report here that the selective disruption of postsynaptic activation in rat S1 by application of a glutamate receptor antagonist inhibits rearrangements in the somatotopic patterning of thalamocortical afferents induced by manipulations of the sensory periphery during the critical period. These findings show that postsynaptic activation has a prominent role in critical period plasticity in S1 cortex.

2-Amino-5-phosphonovalerate↗
PubMed1993

The investigation and rectification of field placement errors in the delivery of complex head and neck fields.

PURPOSE: To evaluate a novel technique for resolving field placement errors into their components and to quantify the improvement in accuracy potentially achievable by translation and rotation of the radiation beam. METHODS AND MATERIALS: One hundred and eighty-five films (both simulator and portal) from seventeen patients receiving radiotherapy to the head and neck region were analyzed in pairs. The computer based comparisons of complex fields with curved edges employed the intersections of perpendiculars from two reference points with the field periphery to define field match points. Field placement errors were resolved into those due to patient motion within the immobilization shell and those due to incorrect beam position, orientation, or shape. RESULTS: The median and the 95 percentile of the distribution of differences between prescribed (simulator) fields and treated (portal) fields referenced to the patients anatomy were 4.4 mm and 8.9 mm, respectively. The analysis suggests that with appropriate translation and rotation of the beam with respect to the immobilization shell these figures could be reduced to 3.1 mm and 8.2 mm, respectively, confirming the large contribution of patient motion within the shell to field placement accuracy. Comparisons between treated fields indicated smaller variability during treatment than between simulation and treatment. CONCLUSION: The perpendicular intersection method described here was found appropriate for the identification of field match points. The distributions of field placement errors were similar to those in a published study of straight edged fields. Translation and rotation of the applied field with respect to the immobilization shell would generally result in only a small improvement in field placement accuracy.

Head and Neck Neoplasms↗