Biomedical subjects

E Lin

Publications and source records attributed to E Lin.

At least 73 records · Page 4Linked to original sources

PubMed1999

Confronting the confounders: the meaning, detection, and treatment of confounders in research.

When one variable is studied to try to explain another, the relationship between them may be biased by a third variable. The bias, known as "confounding," is common and must be minimized in research. This description is deceptively simple, though. Identifying confounding is complex but can be reduced to a stepped procedure. By way of examples, this article describes confounding and how to recognize it.

Bias↗

PubMed1999

Mental health service use: a comparison of treated and untreated individuals with substance use disorders in Ontario.

OBJECTIVE: To determine the prevalence of and factors associated with mental health service use in the past year among respondents with an alcohol or other drug use disorder in a general population survey of Ontario adults. METHOD: Data were obtained from the 1990/1991 Mental Health Supplement to the Ontario Health Survey, which used the University of Michigan Composite International Diagnostic Interview (UM-CIDI). The current study examined 436 respondents aged 15-64 years who met Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria for a substance use disorder in the past year. The 82 respondents who used services for a mental health or substance abuse problem during the past year were compared with the 354 nonusers. Illness severity, disability, health beliefs and attitudes, and predisposing or enabling factors were examined in bivariate and logistic regression analyses. RESULTS: Twenty-two percent of respondents used services in the past year. Having concurrent disorders (comorbidity), troubled relationships with others, and dysfunction in main activity, feeling comfortable talking to a professional about mental health problems, being older and an urban resident, not working or being in school, and having a biological parent with an alcohol or drug problem were all associated with service use. CONCLUSIONS: The results suggest that individual determinants, such as severity of illness, disability, attitudes, and predisposing or enabling variables, all have a role in predicting service use among individuals in the general population who suffer from alcohol and other drug disorders.

Adolescent↗

PubMed1999

P300 habituation patterns: individual differences from ultradian rhythms.

Event-related brain potentials (ERPs) were elicited with auditory stimuli from normal subjects every 10 min. for 10 successive trial blocks to assess ultradian influences on the P300 component. Based on a theoretical analysis of the underlying relationship between background EEG activity and P300 variability, subjects were divided into two groups according to whether P300 amplitude increased or decreased initially over trial blocks. P300 amplitude habituated across trial blocks. P300 latency produced systematic cyclical variation with approximately a 90-min. period that was opposite in phase for the different subject groups. The findings suggest that ultradian rhythms contribute to P300 latency variability. The implications of the results for P300 in applied settings are discussed.

Acoustic Stimulation↗

PubMed1998

The influence of human endotoxemia on CD95-induced apoptosis.

BACKGROUND: The responses of monocyte and neutrophil tumor necrosis factor receptor type 1 (TNFR-1) and TNFR-2 during systemic inflammation have been described previously. Several other members of the TNFR superfamily also appear to have regulatory roles in immunocyte function, including apoptosis. However, the response of these other receptor members, such as CD95, to systemic inflammation is unclear. OBJECTIVES: To compare the response of CD95 with that of TNFR during systemic inflammation and to assess the influence of the inflammatory milieu on CD95 function. SETTING: Adult clinical research center of a university hospital. SUBJECTS AND METHODS: Five healthy male subjects were administered intravenous endotoxin (2 ng/kg), and systemic response was measured by cytokine analysis and receptor expression assays during a 48-hour period. CD95 function during systemic inflammation was assessed using a Jurkat cell bioassay for degree of apoptosis. RESULTS: Monocyte and neutrophil CD95 expression exhibited changes parallel to that of TNFR following endotoxin injection. In contrast to soluble TNFR, which was transiently elevated during endotoxemia, soluble CD95 levels remained unchanged from baseline. Jurkat cells incubated in normal and post-endotoxin serum samples equally exhibited less than 10% spontaneous apoptosis. No soluble CD95 ligand was detectable in experimental human endotoxemia. CONCLUSIONS: Cell-associated CD95 exhibited changes parallel to its receptor family member TNFR following endotoxin administration. Soluble CD95 is present in human serum samples, but the levels remained unchanged following endotoxin administration. No soluble CD95 ligand activity was detectable by enzyme-linked immunosorbent assay or by functional assay. The potential protective role of soluble CD95 in human serum samples against CD95 ligand-induced apoptosis remains to be defined.

Adult↗

PubMed1998

Population pharmacokinetics and pharmacodynamics of pyridostigmine bromide for prophylaxis against nerve agents in humans.

This study was conducted to determine the pharmacokinetics and pharmacodynamics of pyridostigmine given as 30 mg of pyridostigmine bromide every 8 hours in healthy subjects. Plasma pyridostigmine concentration and red blood cell acetylcholinesterase activity were measured in blood samples collected during a 3-week period. Population analysis was performed using standard pharmacokinetic and pharmacodynamic models with the nonlinear mixed-effect modeling software (NONMEM). The pharmacokinetic model that best fit the pyridostigmine plasma levels was a two-compartment open model with first-order absorption, a lag time, and first-order elimination from the central compartment. The pharmacodynamic model that best fit red blood cell acetylcholinesterase activity was an inhibitory Emax model with an effect compartment linked to the central compartment. The results showed that the pharmacokinetics of pyridostigmine bromide are both gender and weight dependent. The pharmacodynamic effect does not lag significantly from the plasma concentration and returns to near normal within 8 hours. With the present dosage regimen of 30 mg every 8 hours, 30% of individuals may not have red blood cell acetylcholinesterase inhibition > 10% at the time of the trough.

Acetylcholinesterase↗

PubMed1998

Nutritional modulation of immunity and the inflammatory response.

The metabolic derangements of the injured or stressed patient are governed by multiple factors that partially include the severity of insult, preexisting illnesses, available energy reserves, and appropriateness of intervention. The normal response to injury is further characterized by the release of proinflammatory and antiinflammatory mediators that exert potent effects on cellular and organ function. Although brief periods of starvation and catabolism are tolerable in otherwise healthy individuals, protracted nutritional deprivation can manifest as immunocompromise, irreversible organ injury, and late mortality. Moreover, patients with severe injuries or preexisting illnesses who exhibit exaggerated inflammatory responses may be further predisposed to such deleterious consequences following the insult. The optimal supply of appropriate nutrients and substrates in such circumstances has often been championed as a necessary means of restoring proper cellular metabolism, wound healing, immune competence, and proper organ function. However, much debate surrounds the present efficacy of nutritional therapy in modulating the immune response associated with injury and stress. This article seeks to assess the merits of nutritional therapeutics in the injured patient through available biological and clinical evidence.

Animals↗

PubMed1998

Impact of improved depression treatment in primary care on daily functioning and disability.

BACKGROUND: Few data are available regarding the impact of improved depression treatment on daily functioning and disability. METHODS: In two studies of more intensive depression treatment in primary care, patients initiating antidepressant treatment were randomly assigned to either usual care or to a collaborative management programme including patient education, on-site mental health treatment, adjustment of antidepressant medication, behavioural activation and monitoring of medication adherence. Assessments at baseline as well as 4 and 7 months included several measures of impairment, daily functioning and disability: self-rated overall health, number of bodily pains, number of somatization symptoms, changes in work due to health, reduction in leisure activities due to health, number of disability days and number of restricted activity days. RESULTS: Average data from the 4- and 7-month assessments in both studies, intervention patients reported fewer somatic symptoms (OR 0.68, 95% CI 0.46, 0.99) and more favourable overall health (OR 0.50, 95% CI 0.28, 0.91). While intervention patients fared better on other measures of functional impairment and disability, none of these differences reached statistical significance. CONCLUSIONS: More effective acute-phase depression treatment reduced somatic distress and improved self-rated overall health. The absence of a significant intervention effect on other disability measures may reflect the brief treatment and follow-up period and the influence of other individual and environmental factors on disability.

Absenteeism↗

PubMed1998

Effect of tape recording on perturbation measures.

Tape recorders have been shown to affect measures of voice perturbation. Few studies, however, have been conducted to quantitatively justify the use or exclusion of certain types of recorders in voice perturbation studies. This study used sinusoidal and triangular waves and synthesized vowels to compare perturbation measures extracted from directly digitized signals with those recorded and played back through various tape recorders, including 3 models of digital audio tape recorders, 2 models of analog audio cassette tape recorders, and 2 models of video tape recorders. Signal contamination for frequency perturbation values was found to be consistently minimal with digital recorders (percent jitter = 0.01%-0.02%), mildly increased with video recorders (0.05%-0.10%), moderately increased with a high-quality analog audio cassette tape recorder (0.15%), and most prominent with a low-quality analog audio cassette tape recorder (0.24%). Recorder effect on amplitude perturbation measures was lowest in digital recorders (percent shimmer = 0.09%-0.20%), mildly to moderately increased in video recorders and a high-quality analog audio cassette tape recorder (0.25%-0.45%), and most prominent in a low-quality analog audio cassette tape recorder (0.98%). The effect of cassette tape material, length of spooled tape, and duration of analysis were also tested and are discussed.

Humans↗

PubMed1998

Medication management of depression in the United States and Ontario.

OBJECTIVE: To compare rates of contact for mental problems and receipt of appropriate antidepressant medication management for persons in the general population with major depression in the United States and Ontario, Canada. DESIGN: Survey using the U.S. National Comorbidity Survey and the Mental Health Supplement of the Ontario Health Survey. PARTICIPANTS: All persons with major depression as described in DSM-III-R in the previous 12 months, from a multistage random sample of persons aged 21 to 54 years living in households in the United States (n = 574) and Ontario (n = 250) in 1990. MEASUREMENTS AND MAIN RESULTS: Self-reported contact with general medical or mental health specialty providers for mental problems and appropriate medication management, defined as a combination of antidepressant medication use and four or more visits to any provider within the previous 12 months, were the main outcome measures. The proportion of depressed persons receiving appropriate management was lower in the United States than in Ontario (7.3% vs 14.9% in Ontario, adjusted odds ratio [AOR] 95% CI 0.4; 95% confidence interval [CI] 0.2, 0.8). This difference was largely the result of fewer Americans than Canadians having any mental health care from general medical physicians (9.6% in the United States vs 25.8% in Ontario; AOR 0.3; 95% CI 0.1, 0.5) rather than from specialty providers (20.8% in the United States vs 28.9% in Ontario; AOR 0.7; 95% CI 0.4, 1.1). These between-country differences were much greater for the poor than for those with higher incomes. The Ontario-United States AOR of making contact with either type of clinical provider was 7.5 (95% CI 2.7, 20.7) for lowest-income persons but 2.1 (95% CI 0.3, 5.6) for highest-income persons. The proportions of depressed recipients of any mental health care who received appropriate management were similar between countries (23.9% in the United States vs 27.7% in Ontario; AOR 0.8; 95% CI 0.3, 1.7). CONCLUSIONS: Most persons with depression in the United States and Ontario do not receive appropriate medication management. The rate of appropriate medication management in the United States relative to Ontario is lower largely because there is less contact with general medical physicians for mental problems, especially for the poor. Economic barriers, rather than knowledge and attitudinal factors, appear to explain this difference.

Adult↗

PubMed1998

Significance of early tubular extraction in the first minute of Tc-99m MAG3 renal transplant scintigraphy.

Renal transplant perfusion curves obtained using Tc-99m MAG3 differ from those with Tc-99m DTPA. The perfusion curve can be divided into a first phase (up to the first-pass peak) and a second phase (the curve after the initial peak). The second phase of the MAG3 perfusion curve is usually ascending in contrast to the descending Tc-99m DTPA curve. This ascending MAG3 curve reflects early tubular extraction of MAG3. However, the second phase of the MAG3 curve is sometimes flat or descending. We hypothesized that a flat or descending curve reflects poor early tubular extraction and therefore graft dysfunction. Ninety-two studies of 59' renal transplant patients were retrospectively reviewed. The second phase of the perfusion curve was visually classified as ascending, flat, or descending. 77.2% of studies had ascending curves, 16.3% flat curves, and 6.5% descending curves. A descending curve had a positive predictive value (PPV) of 100% for medical graft dysfunction, while a flat curve had a PPV of 93.3%. A nonascending second phase curve was specific (96.4%) but not sensitive (33.9%) for graft dysfunction. Patients with acute tubular necrosis were not significantly more likely to have a nonascending curve than those with acute rejection. There was no significant difference in creatinine level between patients with medical graft dysfunction and ascending vs. nonascending curves. A nonascending second phase Tc-99m MAG3 perfusion curve is predictive for graft dysfunction. An ascending curve is nonspecific and can be seen in both normally and poorly functioning grafts.

Adult↗

PubMed1998

Glottographic signal perturbation in biomechanically different types of dysphonia.

Glottographic signals may be superior to acoustic signals for tracking glottal source perturbations, since supraglottal vocal tract effects on glottographic signals are relatively minimal compared with the acoustic signal as measured beyond the lips. This study compared the ability of differing signals to differentiate among normal voices and abnormal voices that were due to two categories of biomechanical disease. Acoustic, electroglottographic, and photoglottographic signals recorded during vowel phonation sustained by 26 normal subjects and 65 patients were measured for perturbations of frequency and amplitude. One-way analysis of variance (ANOVA) revealed that amplitude perturbation measures from photoglottographic signals significantly differentiated neuromuscular from mass lesion sources of dysphonia. Acoustic and electroglottographic signal perturbations differentiated between normal and abnormal voices but did not distinguish between the dysphonic characteristics of neuromuscular disorders and those of mass lesions of the vocal folds.

Acoustics↗

PubMed1998

Psychiatric morbidity and physician visits: lessons from Ontario.

OBJECTIVES: The authors examine the association between psychiatric morbidity and visits to general practitioners and family practitioners in Ontario, Canada. METHODS: A nested set of hypotheses were posed to account for different levels of use among persons with differing levels of psychiatric morbidity. The sample of 8,116 is drawn from a comprehensive household survey of physical and mental health that included the UM-CIDI standardized diagnostic interview. RESULTS: The findings suggest that persons with psychiatric disorders make more visits than can be accounted for by sociodemographic factors, medical status, access, or by intentional use of the general medical system for mental health treatment. CONCLUSIONS: Psychiatric morbidity is associated with higher rates of health service use. This effect is strongest among persons with multiple psychiatric disorders.

Adolescent↗

PubMed1998

Efficacy of nutritional pharmacology in surgical patients.

The present article reviews the current concepts of immune enhancement through nutritional support for the surgical patient as they are derived experimentally and clinically. Although the potential for altering outcome in surgical patients through nutritional enhancement exists, the authors caution against overzealous application of laboratory data in the clinical arena. Available clinical studies have, at best, only demonstrated modest benefits. It is appropriate that the current literature be critically reviewed to assess the efficacy of the agent(s) purported to be of clinical benefit. Although present reports of immune-enhancing nutrition regimens demonstrate no overwhelming benefits in the critically ill or immunocompromised patient, the pursuit of this science remains undaunted. Lessons learned from the past are leading to reinvestigations in the laboratory, as well as better designs of clinical trials that are free of distracting post-hoc analysis and performed clearly in an intention-to-treat manner.

Amino Acids↗

PubMed1998

Long-term therapy with the guanine nucleoside analog penciclovir controls chronic duck hepatitis B virus infection in vivo.

Ducks congenitally infected with duck hepatitis B virus (DHBV) were treated with the antiviral guanine nucleoside analog penciclovir for 12 or 24 weeks at a dosage of 10 mg/kg of body weight per day. By the completion of both 12 and 24 weeks of therapy, molecular hybridization studies of the liver tissue revealed that the viral DNA, RNA, and protein levels were significantly reduced compared to those in the placebo-treated controls. Penciclovir treatment for 12 or 24 weeks was not associated with any toxicity, establishing the efficacy and safety of long-term penciclovir therapy in chronic DHBV infection.

Acyclovir↗

PubMed1998

Psychiatric disorder onset and first treatment contact in the United States and Ontario.

OBJECTIVE: The authors describe the timing of the first treatment contact following new-onset DSM-III-R mood, anxiety, and addictive disorders in community samples from the United States and Ontario, Canada, before and after passage of the Ontario Health Insurance Plan. METHOD: The authors drew data from the National Comorbidity Survey (NCS) (N=8,098) and the mental health supplement to the Ontario Health Survey (OHS) (N= 9,953). They assessed psychiatric disorders with a modified version of the Composite International Diagnostic Interview; they also assessed retrospectively age at disorder onset and first treatment contact. They used the Kaplan-Meier method to generate time-to-treatment curves and survival analysis to compare time-to-treatment intervals across the two surveys. RESULTS: The overall time-to-treatment curves revealed substantial differences between disorders that were consistent across the two surveys. In both surveys, panic disorder had the highest probability of first-year treatment (NCS, 65.6%; OHS supplement, 52.6%), while phobia (NCS, 12.0%; OHS supplement: 6.5%) and addictive disorders (NCS, 6.4%; OHS supplement, 4.2%) had the lowest in both surveys. Retrospective subgroup analysis suggests that before the passage of the Ontario public insurance plan, the likelihood of receiving treatment in the year of disorder onset was greater in Ontario than in the United States but that this relationship reversed following passage of the Ontario plan. During this period, the authors observed no significant between-country differences in the probability of prompt treatment of adults with 12 or fewer years of education. CONCLUSIONS: These results challenge the assumption that the universal health insurance plan in Ontario promotes greater access to mental health services than is available in the United States for vulnerable groups. Marked differences between disorders in the speed to first treatment suggest that in both countries, clinical factors play an important role in the timing of the initial decision to seek treatment.

Adult↗

PubMed1998

Variations in mental health needs and fee-for-service reimbursement for physicians in Ontario.

OBJECTIVES: The study examined the match between mental health needs and physician fee-for-service reimbursements for mental health care within age and gender groups and health planning regions in Ontario, Canada. METHODS: Indicators of need (mental disorder, reported disability, and self-rated mental health) from an epidemiologic survey of 9,953 Ontario household residents were compared with per capita reimbursement rates derived from an administrative data set containing all fee-for-service expenditures for mental health care paid by the provincial health plan. RESULTS: Few gender differences were found in overall need, but need varied significantly by age. Those in greatest need were adolescent males and females, who had rates of need from two to four times higher than older respondents. Regional variations in need were less evident. By contrast, per capita reimbursement showed marked gender differences, with rates for women generally twice the rates for men. Considerable variations in reimbursement were also found across age groups; these variations did not match variations in need. Highly urbanized areas had per capita reimbursement rates between two and four times the rates for less populated areas. CONCLUSIONS: Despite Ontario's universal-access health care system, notable discrepancies between need and resource use are evident for males, adolescents, and residents of less urbanized areas. Solutions require a combination of public education, provider training, attention to physician availability and practice patterns, and continuous monitoring of how resources are allocated relative to need.

Adolescent↗

PubMed1998

Life after chi-squared: an introduction to log-linear analysis.

Chi-squared tests are used to examine the relationships among categorical variables. However, they are difficult to use and interpret when more than 2 variables are involved. In such cases, it is better to use a related statistic, called log-linear analysis. This article is an introduction to log-linear models, illustrating how they can be used to tease apart relationships among several variables in looking at the factors associated with photonumerophobia.

Chi-Square Distribution↗

PubMed1997

Differences in the use of psychiatric outpatient services between the United States and Ontario.

BACKGROUND: The relation between health insurance and the use of mental health services is unclear. We compared the use of outpatient services for psychiatric problems in the United States and Ontario, Canada, among young and middle-aged adults according to self-reports of disorders listed in the Diagnostic and Statistical Manual of Mental Disorders (third edition, revised) and to other indicators of need. METHODS: We analyzed two general-population surveys carried out separately in the United States and Ontario in 1990 that used identical assessments of need for services and questions about their use by persons 15 to 54 years of age. RESULTS: Respondents in the United States were significantly more likely than those in Ontario to report having had psychiatric disorders, poor mental health, or workdays lost or cut short because of psychiatric problems in the previous year. A significantly higher proportion of respondents in the United States (13.3 percent) than in Ontario (8.0 percent) had obtained outpatient treatment in the previous 12 months for psychiatric problems. However, an analysis of subgroups found that the higher probability of the use of services in the United States was confined to people with less severe mental illness. The average number of visits did not differ significantly between the two countries among patients who had similar numbers of psychiatric disorders over the same time periods. There was a stronger match in Ontario than in the United States between the use of services and the measures of perceived need we considered. CONCLUSIONS: Although the mental health care system in the United States provides treatment to a larger proportion of the population than that in Ontario, the match between some measures of need and treatment is not as strong in the United States. Any plans to expand coverage for psychiatric disorders in the United States must address this problem.

Adolescent↗