Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Individual variability”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79Linked to original sources
PubMed2001

Factors related to quality of life in breast cancer patients receiving chemotherapy.

This descriptive correlation study investigated the relationship among individual characteristics, disease characteristics, psychological factors (anxiety, depression, self-esteem), social support, and quality of life in patients with breast cancer receiving chemotherapy. One hundred and fifty women from nine Taipei area hospitals were surveyed with a structured questionnaire. The total quality of life index for breast cancer patients was about average (M = 19.88). The family factor scored highest for importance and satisfaction with quality of life. Patients showed the most dissatisfaction with the health factor. Of the individual characteristics affecting patient quality of life, number of children and social status were statistically significant (p < .05). Of the disease characteristics, the stage of the disease, the commencement of chemotherapy, and the number of chemotherapy treatments were statistically significant (p < .05). The psychological factors were significantly related to patients' quality of life (p < .05). Social support of both relatives and health professionals was significantly related to patients' quality of life (p < .01). Of the four independent variables (individual characteristics, disease characteristics, psychological factors and social support), the most influential factor affecting breast cancer patients' total quality of life was the psychological factor of self-esteem (p < .001). The findings can assist nurses to plan and improve the quality of breast cancer care in terms of understanding the factors affecting patients' quality of life.

Adult↗
PubMed1996

The development of opiate addiction in the rat.

Opiate intake was studied in rats, which were given free choice between water and etonitazene (ETZ) solutions (2, 4, and 8 mg/l) for 30 weeks. After an abstinence of 19 weeks, the opiate was reoffered. The long-term course of intake could be subdivided in three phases: a period of controlled intake (25 weeks), a period of increasing consumption (week 25-30), and the stage of drug addiction (retest). During controlled intake, environmental and individual variables reversibly influenced ETZ intake (high intake in socially deprived and in subordinate rats, low intake in group-housed and in dominant rats). After 25 weeks of situation-specific intake, the rats spontaneously increased ETZ consumption. In the retest after long-term ETZ-abstinence, their intake was strongly increased compared to both their own intake before and to that of drug-naive controls. ETZ intake could no longer be influenced by environmental, gustatory, or individual factors ("loss of control") indicating opiate addiction. In contrast, rats that have formerly had forced administration by means of a 2 mg/l ETZ solution did not become addicted. Signs of opiate withdrawal, however, occurred in both series of forced and voluntary intake. Principles of the temporal development of opiate addiction are compared with those described previously for ethanol addiction.

Animals↗
PubMed1990

Prognostic factors in the radiotherapy of Graves' ophthalmopathy.

Between April 1968 and February 1988, 311 patients with symptomatic and progressive Graves' ophthalmopathy were treated with megavoltage orbital radiotherapy. The patients were divided into three groups: I (156 patients) treated with 20 Gy/2 weeks; II (69 patients) treated with 30 Gy/3 weeks, and III (a most recent set of 86 patients) received 20 Gy/2 weeks. The degree of eye involvement was evaluated numerically before and after therapy for each of five parameters: soft tissue signs, proptosis, eye muscle impairment, corneal involvement, and sight loss. Pre-treatment and current thyroid diagnosis and status were also noted. To evaluate the effects of radiotherapy alone, follow-up was terminated at the time any eye surgery was done; for those not treated surgically the minimum follow-up was 12 months. Because there were significant demographic differences between the patient groups, the results of each group were analyzed separately. A stepwise linear regression analysis was performed to determine if there were any significant variables affecting outcome. Based on these data formulae were derived which enable outcome to be predicted in any patient. Before therapy more than 90% of patients in all groups had soft tissue and eye muscle involvement, whereas 65-75% had proptosis and about half 50% had some degree of sight loss. Radiotherapy arrested progression of ophthalmic parameters in all but 1-6% of the patients. Objective and symptomatic improvement was noted for all parameters assessed, but there was marked individual variability. The best responses were noted for soft tissue, corneal involvement, and sight loss; however over half the patients had some improvement in eye muscle function and proptosis. Factors which resulted in less favorable outcome included male gender, advanced age, need for concurrent therapy for hyperthyroidism, and no history of hyperthyroidism. No complications have been observed. No significant differences in outcome were observed between the two dosage schedules. Following radiotherapy 29% of patients subsequently underwent some form of eye surgery, mostly eye muscle surgery to correct diplopia. After radiotherapy corticosteroid therapy was stopped without relapse in 76%. Orbital radiotherapy can result in improvement in signs and symptoms of Graves' ophthalmopathy in the majority of patients. For the remainder of patients the disease manifestations can be stabilized to allow functional surgical correction.

Connective Tissue↗
PubMed1995

Individualised low-dose alglucerase therapy for type 1 Gaucher's disease.

Previous studies have shown that enzyme supplementation therapy with alglucerase for type 1 Gaucher's disease is effective at doses of 30-130 U/kg per month. Since both the clinical presentation and the response to therapy in Gaucher's disease are highly variable, individual dosing seems indicated. This notion, as well as the high costs of alglucerase and the unknown long-term side-effects, led us to investigate the efficacy of an individualised very low dose of alglucerase. Twenty-five adults with symptomatic type 1 Gaucher's disease (thirteen splenectomised) received alglucerase 1.15 U/kg three times a week (15 U/kg per month). Every 6 months, the dose was halved, maintained, or doubled, according to the response (based on haematological variables and liver and spleen volume). After 6 months of treatment, eighteen (72%) patients had a response (seventeen moderate, one good). After 12 months (in nineteen patients) and 18 months (in seven patients), all had sustained improvement. Severe splenomegaly resulted in slower haematological responses. Our results are similar to those obtained by others with higher-dose regimens and better than a low-dose regimen of 10U/kg every 2 weeks. We conclude that very low initial doses of alglucerase, when administered frequently, are effective and cost-saving in the treatment of type 1 Gaucher's disease.

Adult↗
PubMed2001

Comprehensive evaluation of community-based diabetic patients: effect of feedback to patients and their physicians: a randomized controlled trial.

OBJECTIVE: To demonstrate improvements in diabetes care stimulated by comprehensive evaluation of community-based diabetic patients with feedback to the patients and their physicians. RESEARCH DESIGN AND METHODS: A comprehensive evaluation of community-based diabetic patients with annotated reporting of results to both patients and their physicians (universal intervention) was followed by random assignment of 50% of patients to individual counseling (randomized intervention). In four communities, two large and two small, 55 type 1 and 376 type 2 diabetic patients were recruited, evaluated, and reassessed at 1 year. Outcome measures were HbA1c, serum cholesterol, and systolic and diastolic blood pressure. RESULTS: There were significant improvements in all outcome measures for type 2 diabetic patients randomized to individual counseling (P = 0.03; follow-up rate 84%) and significant improvements in all outcome measures for all high-risk type 2 patients (highest P value = 0.004; follow-up rate 85%). CONCLUSIONS: Comprehensive evaluation of diabetic patients at the community level with annotated reporting of results to the patients and their physicians was associated with improvement of mean HbA1c, cholesterol, and systolic and diastolic blood pressure, particularly in patients in high-risk status for these outcome variables. Individual counseling of 50% of patients, randomly selected, enhanced these results.

Blood Pressure↗
PubMed1996

Molecular epidemiology: insights into cancer susceptibility, risk assessment, and prevention.

Recent molecular epidemiologic research provides compelling new evidence that environmental factors are major contributors to human cancer and that their risks are strongly influenced by genetic and acquired susceptibility. In particular, molecular epidemiology has demonstrated substantial variability in biologic response to carcinogens and suggests that certain groups-such as the very young, those with predisposing genetic traits or nutritional deficits, and even certain ethnic groups-are likely to have greater risk from selected exposures than other members of the population. This work implies that major gains in prevention of cancer, which will claim more than 554 000 American lives this year, will necessitate health and regulatory policies that protect these more susceptible groups and individuals from risks of man-made and naturally occurring environmental carcinogens. The specific implication from this research is that, to be effective in prevention, risk assessments developed in support of these policies by regulatory bodies, such as the Environmental Protection Agency, should reflect the available scientific data on individual variability in both exposure and susceptibility.

DNA Repair↗
PubMed1990

The effects of androgens and estrogen on the external morphology and electric organ discharge waveform of Gnathonemus petersii (Mormyridae, Teleostei).

The effects of androgens and estrogen on the external morphology and electric organ discharge (EOD) waveform in Gnathonemus petersii, a weakly discharging electric fish, were investigated. Following preimplant data collection, juvenile and adult fish were gonadectomized and implanted with silastic capsules containing either high or low doses of testosterone (T), dihydrotestosterone (DHT), estradiol-17 beta (E2), or cholesterol. One group of fish was treated with high doses of DHT + E2. Radioimmunoassays revealed that low-dose implants resulted in plasma T levels comparable to and high-dose implants about sixfold greater than those found in adult males imported during breeding season. High-dose E2 implants resulted in higher plasma E2 levels in adults than those in juveniles. At either dose, both androgens induced male-like indentations in the dorsal margin of the anal fin of juveniles and adult females by 4 weeks postimplant. Both low and high doses of T decreased the peak power spectrum frequency (PPSF) of Fourier transformations of EODs and increased the durations of phases 2 and 3 of the EOD in juveniles and adults, but the high doses caused more rapid and profound effects. The two doses of T caused opposite effects on the durations of phases 1 and 4 juveniles. The low dose of T decreased the durations of phases 1 and 4, while the high dose increased them. In adults, the high dose of T increased the duration of phase 1, but had inconsistent effects on the duration of phase 4. Total EOD durations were increased by both doses of T in juveniles, while adults showed inconsistent effects possibly due to individual variability in hormone sensitivity. Compared to T, DHT exerted similar, but less dramatic effects on all measures, but only at high doses. E2 significantly increased adult PPSFs, the first such finding in a mormyrid species. E2 had no effects on juvenile PPSFs, or on adult or juvenile EOD phase durations. The effects of DHT + E2 on PPSF and phases 2 and 3 were similar to those of DHT alone. These findings demonstrate quantifiable steroid-dependent plasticity in the durations of individual phases of EODs in an electric fish and are the first to show that the external morphology in Gnathonemus petersii is androgen-dependent. The results are discussed with regard to methodological considerations and hormone studies involving sex differences in EODs reported for this and other species.

Animals↗
PubMedDate not supplied

Lymph node reactivity and microvessel density in neck metastases of unknown primary squamous cell carcinoma.

BACKGROUND: Neoangiogenesis and the immune response are important mechanisms in metastasis development. AIM: to evaluate lymph node reactivity and microvessel density in neck metastasis of occult primary squamous cell carcinoma considering their histological and clinical variables. STUDY DESIGN: retrospesctive case-series. METHOD: 19 patients with neck metastasis of occult primary squamous cell carcinoma who underwent neck dissection between 1983 and 2000 were selected. The lymph nodes were reevaluated on the type of reactivity in both the cortical and paracortical areas, and the metastasis were assessed as to grade, desmoplasia, necrosis and microvessel density (CD34). The relationship between histological and clinical variables was evaluated. RESULTS: the median microvessel density was 91 vessels/mm2, varying from 28 to 145. Paracortical hyperplasia was more common in patients below 55 years of age (90%x44%, p=0.05), but there was no relationship between reactivity patterns and microvessel density with prognosis. The disease-free survival was 52% in 3 years, being similar in both groups, with higher or lower microvessel densities. CONCLUSION: microvessel density in neck metastasis of occult primary squamous cell carcinoma had a great individual variability. It wasnt possible to establish the relationship between microvessel density and the clinical or histological variables studied.

Carcinoma, Squamous Cell↗
PubMed2004

Understanding variability in time spent in selected locations for 7-12-year old children.

This paper summarizes a series of analyses of clustered, sequential activity/location data collected by Harvard University for 160 children aged 7-12 years in Southern California (Geyh et al., 2000). The main purpose of the paper is to understand intra- and inter-variability in the time spent by the sample in the outdoor location, the location exhibiting the most variability of the ones evaluated. The data were analyzed using distribution-free hypothesis-testing (K-S tests of the distributions), generalized linear modeling techniques, and random-sampling schemes that produced "cohorts" whose descriptive statistical characteristics were evaluated against the original dataset. Most importantly, our analyses indicate that subdividing the population into appropriate cohorts better replicates parameters of the original data, including the interclass correlation coefficient (ICC), which is a relative measure of the intra- and inter-individual variability inherent in the original data. While the findings of our analyses are consistent with previous assessments of "time budget" and physical activity data, they are constrained by the rather homogeneous sample available to us. Owing to a general lack of longitudinal human activity/location data available for other age/gender cohorts, we are unable to generalize our findings to other population subgroups.

Activities of Daily Living↗
PubMed2001

Efavirenz plasma levels can predict treatment failure and central nervous system side effects in HIV-1-infected patients.

OBJECTIVE: Limited information exists on the clinical usefulness of drug level monitoring for efavirenz, a once-daily non-nucleoside reverse transcriptase inhibitor (NNRTI). The aim of this study was to determine whether efavirenz plasma concentration monitoring could predict treatment failure and central nervous system (CNS) tolerability. METHODS: Blood samples were obtained from 130 HIV-infected patients receiving efavirenz in combination with other antiretroviral agents for more than 3 months. Efavirenz plasma concentrations were measured by high-performance liquid chromatography. An evaluation of CNS side-effects was performed and the viral load, CD4 cell count and other clinical and laboratory data were assessed. In 85 patients, these measures were repeated at 3 month intervals. RESULTS: Efavirenz plasma levels (n = 226) were measured at an average of 14 h after drug intake. Drug concentrations ranged from 125 to 15230 microg/l (median 2188). Large inter-patient (CV 118%) and limited intra-patient (CV 30%) variabilities were observed in efavirenz levels. Virological failure was observed in 50% of patients with low efavirenz levels (< 1000 microg/l) versus 22 and 18% in patients with 1000-4000 microg/l or more than 4000 microg/l, respectively. CNS toxicity was approximately three times more frequent in patients with high efavirenz levels (> 4000 microg/l) compared with patients with 1000-4000 microg/l. CONCLUSION: Treatment failure and CNS side-effects are associated with low and high efavirenz plasma levels, respectively. The important inter-individual variability in efavirenz levels strongly argues for dose adjustment on the basis of therapeutic drug monitoring to optimize treatment.

Adult↗
PubMed2005

The pharmacogenetics of asthma: an update.

Responses to the three major classes of asthma therapy, beta-agonists, leukotriene antagonists and inhaled corticosteroids, demonstrate wide inter-individual variability. Moreover, both asthma and the traits measured in response to asthma therapy, including forced expiratory volume at 1 s, are highly heritable. This indicates that genetics may play a prominent role in the determination of the therapeutic response to asthma. The human genetic association trials that investigate responses to each of the three major classes of asthma therapy will be summarized, and recent findings in the literature highlighted. Altogether, the available data indicate that genetics influences the likelihood of an individual responding to a given therapy, indicating that, in the future, optimal care for individuals with asthma may include genetic testing.

Adrenal Cortex Hormones↗
PubMed1999

Fifteen-year reproducibility of natural head posture: A longitudinal study.

Natural head posture continues to be widely used as the logical reference position for the evaluation of craniofacial morphology. The basic underlying premise is that the long-term clinical reproducibility (variability) of natural head posture is significantly less than the variability of conventional reference planes with respect to the vertical. This study reports the 15-year longitudinal reproducibility of natural head posture. Twenty Chinese adults in Hong Kong, who had initial natural head posture radiographs at age 12 years, were followed up and had repeated cephalograms after 15 years. The method error (reproducibility) after 15 years was 2.2 degrees, which compared favorably with the 5-year reproducibility (method error = 3.0 degrees ) and the 5 to 10 minutes reproducibility (method error = 1.9 degrees ). The individual variability of natural head posture reproducibility increased slightly over time. After 15 years the variance of natural head posture (4.8 degrees [= 2.2(2)]) remains significantly less than the variance of intracranial reference planes to the vertical (25 degrees to 36 degrees ). Cephalometric analyses based on natural head posture therefore remain valid over time.

Adult↗
PubMed1998

Long-term variability of serum lipoprotein(a) concentrations in healthy fertile women.

Lipoprotein(a) is a unique lipoprotein with atherothrombogenic properties. Although its blood concentration is mainly genetically determined, various factors exist which may cause variability. These may influence the clinical use of the results. We studied lipoprotein(a) biological variation by a rate nephelometric assay over a period of two years in a population of healthy fertile women. The study was performed in 12 volunteers, healthy subjects with various lipoprotein(a) concentrations, by monthly determinations during one year and a single determination one year later, together with measurements of total, high density lipoprotein and high density lipoprotein2 cholesterol, triglycerides and apolipoproteins A1 and B. The intra-individual variability of lipoprotein(a) ranged between 4 to 20%, with three subjects showing a coefficient of biological variation higher than 15%. In absolute terms, the difference between two determinations could represent 0.44 g/l or 50% of the mean value. This study suggests that physiological lipoprotein(a) variations should be taken into account for clinical purposes, especially in patients in need of thorough risk evaluation.

Adult↗
PubMedDate not supplied

[The effect of 2 lipid emulsions on platelet function].

We examined the effect on platelet aggregation and activation and the production of eicosanoids in nonseptic critical patients of two lipidic emulsions administered with total parenteral nutrition. The two lipidic emulsions, Intralipid (20% of long chain triglycerides) and Lipofundina (10% each of long and medium-chain triglycerides), of differing essential fat acid content, provided 43% of the non-protein calorific requirements calculated for each patient. There were no other variables in the parenteral nutrition administered: the patients were distributed in two groups on a randomized basis according to the type of lipids received. We assessed the parameters demonstrating platelet function before parenteral nutrition, and after 4 and 7 days of such nutrition. Throughout the study, platelet aggregability was seen not to differ significantly from normal, even though the activation parameters controlled, beta TG and PF4, were from the outset significantly higher than normal; the thromboxane B2 averages calculated remained high, with wide individual variability, while averages for 6-keto-PGF1 alpha [correction of 0], which were initially high, showed a tendency (not statistically significant) to drop after 4 and 7 days nutrition. We did not observe that the administration of LCT or MTC/LCT led to changes in platelet aggregation and/or activation in the patients studied.

Adolescent↗
PubMed1997

The impact of HIV on emotional distress of infected women: cognitive appraisal and coping as mediators.

This study examined the role of psychological factors as mediators of the impact of HIV-related stressors on emotional distress of a clinic-based sample of 264 HIV+ women. Based upon Lazarus and colleagues' cognitively oriented theory of stress and coping, causal modeling was used to test for mediating effects of cognitive appraisal (intrusive thoughts and perceived stigma) and coping variables (avoidance and fatalism) on emotional distress within the context of HIV-related stressors (functional impairment and work performance impairment). The findings supported the mediating effects of cognitive appraisal but not of the coping variables. Consistent with theory, the effect of HIV-related stressors on emotional distress was indirect through cognitive appraisal; however, there were no significant direct effects of HIV-related stressors, fatalism or avoidance on emotional distress. The causal model accounted for significant portions of variance in emotional distress (R2 = .49) and the model fit, as a whole, was more than adequate. The findings indicate that how HIV+ women think about HIV-related stressors is an important factor that may account for individual variability in the ability to maintain a sense of subjective well-being in the face of a devastating fatal disease.

Adaptation, Psychological↗
PubMed1998

Cerebral interregional correlations of associative language processing: a positron emission tomography activation study using fluorine-18 fluorodeoxyglucose.

Even though there have been numerous positron emission tomography (PET) activation studies on the perfusional and metabolic bases of language processing, little is known about the intracerebral functional network of language and cognitive processes. It was the aim of this study to investigate the cerebral interregional correlations during voluntary word association versus word repetition in healthy subjects to gain insight into the functional connectivity of associative speech processing. Due to individual variability in functional anatomy, the study protocol was designed as an averaged single-subject study. Eight healthy volunteers performed a verbal association task during fluorine-18 fluorodeoxyglucose (18F-FDG) PET scanning. Two different tasks were performed in randomized order: (a) word repetition (after auditory presentation of nouns) as a control condition, and (b) word association (after auditory presentation of nouns) as a specific semantic activation. The regional metabolic rate of glucose (rMRGlu) was calculated after brain regionalization [112 regions of interest on individual 3D flash magnetic resonance imaging (MRI)] and PET/MRI realignment. Statistical analysis was performed for comparison of association and repetition and for calculation of interregional correlation coefficients during both tasks. Compared with word repetition, word association was associated with significant increases in rMRGlu in the left prefrontal cortex, the left frontal operculum (Broca's area) and the left insula, indicating involvement of these areas in associative language processing. Decreased rMRGlu was found in the left posterior cingulum during word association. During word repetition, highly significant negative correlations were found between the left prefrontal cortex, the contralateral cortex areas and the ipsilateral posterior cingulum. These negative correlations were almost completely eliminated during the association task, suggesting a functional decoupling of the strict intercorrelation pattern.

Adult↗
PubMed1997

Male-dependent variability of fertilization and embryo development in two bovine in vitro fertilization systems and the effects of casein phosphopeptides (CPPs).

This study investigated the effects of semen from five different bulls and two different ejaculates of the same bull on penetration, cleavage, blastocyst formation, and cell allocation in bovine blastocysts produced in vitro. Casein phosphopeptides (CPPs) were tested for their ability to enhance fertilization and minimize variability among bulls and ejaculates. In Experiment 1, the BO-fertilization system was employed. Penetration and polyspermy both displayed great variation among bulls and between ejaculates, whereas no significant differences were observed in cleavage and blastocyst-formation rates. Similar variability was observed in penetration, polyspermy, cleavage, blastocyst-formation rates and cell allocation and distribution when the two fertilization systems, TALP and BO, were compared in Experiment 2. The BO-system supported penetration and polyspermy better (P < 0.05) than the TALP-system, whereas the TALP-system was superior (P < 0.05) in supporting cleavage and blastocyst formation. Significant interactions existed between bulls and the fertilization system employed. It is concluded that the success of in vitro fertilization is markedly dependent on individual bulls as well as on ejaculates from the same bull. CPPs are able to enhance penetration and embryo development in certain bulls or ejaculates and thus contribute to reducing the degree of individual variability, but they do not generally improve the success of bovine embryo production in vitro.

Animals↗
PubMed1995

Changes in serotonin metabolism during treatment with the aldehyde dehydrogenase inhibitors disulfiram and cyanamide.

The effect of the aldehyde dehydrogenase inhibitors disulfiram (Antabuse) and cyanamide (calcium carbimide, Dipsan) on the metabolism of serotonin measured as relative amounts of the metabolites 5-hydroxyindole-3-acetic acid and 5-hydroxytryptophol in urine were studied in alcoholic patients. Sixteen out of 23 patients receiving drug therapy showed elevated excretion of 5-hydroxytryptophol. However, there was a marked, 15-fold, variability in 5-hydroxytryptophol excretion rate between patients. A high degree of variability was also seen in another group of patients studied before and after introduction of drug therapy. When patients were followed during the dose interval, a time-dependent response after each single dose could be observed. The disulfiram response lasted over the course of several days whereas the response to cyanamide lasted for less than 12 hr. It is concluded that treatment with disulfiram and cyanamide affects serotonin metabolism leading to increased production of 5-hydroxytryptophol, but there is a marked inter-individual variability in degree of response.

Adult↗