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Biomedical subjects

M H Liang

Publications and source records attributed to M H Liang.

At least 37 records · Page 2Linked to original sources
PubMed1999

Application of statistical graphics to facilitate selection of health status measures for clinical practice and evaluative research.

Relatively little attention has been directed towards the study of the ability of health status measures to demonstrate clinically meaningful change. We examined the use of Tukey's stem and leaf plots and time-path diagrams to assess the sensitivity of a health status measure in showing change. We compared the evaluative characteristics of the physical ability scales of the Sickness Impact Profile (PSIP), and the SF-36 (PSF-36), in 54 consecutive patients undergoing elective primary or revision total hip replacement. To validate time-path diagrams, we used patients' perception of change in physical function (transition question) as an external standard. At baseline there was no clustering at the end of the scales. At 3 months, the distribution of the PSIP showed a clustering at the upper end of the scale and a strong skewness towards lower scores, whereas the PSF-36 showed a wide distribution of the scores. Seven out of 54 patients had perfectly normal scores on the PSIP at 3 months, whereas one patient had a perfect score on the PSF-36 at 3 months. In time-path diagrams the response pattern of the PSIP was similar to that of the PSF-36, with the exception of the patient-fifth with the best initial health status. The overall impression of the time-path diagram for these patients was that of no change. A closer examination revealed that half of these patients had horizontal or downwards sloping lines, indicating a worsening in physical function. However, all these patients perceived themselves as improved. The PSIP has a ceiling effect for patients with relatively good physical health. It was concluded that stem and leaf plots are useful in the assessment of health status measures, for discriminative purposes, to differentiate patients' health cross-sectionally. Time-path diagrams stratified by baseline health status with information on patients' perception or valuation of change provide useful information about the ability of an instrument to detect change over time.

Arthroplasty, Replacement, Hip↗
PubMed1999

Association of silicone breast implants with immunologic abnormalities: a prospective study.

PURPOSE: To study the possible association of silicone-breast-implant exposure and immunologic abnormalities within the Nurses' Health Study, an ongoing prospective cohort study of women. SUBJECTS AND METHODS: From this cohort, we randomly selected 200 women who had been exposed to silicone breast implants and who had never reported connective tissue diseases during 14 years of follow-up, and 500 age-matched, nonexposed women, including 100 with definite connective tissue diseases validated by medical record review, 100 with at least one symptom of a connective tissue disease, 100 with diabetes, and 200 healthy controls. Assays for antinuclear antibodies (ANA), including anti-dsDNA, anti-ssDNA, anti-Sm/RNP/Ro/La, and anti-Scl-70, rheumatoid factor, immunoglobulins, serum complement, and C-reactive protein level, and anticardiolipin, antithyroglobulin, antithyroid microsomal, and antisilicone antibodies were performed by standard techniques in blood samples collected in 1989 or 1990 before collection of silicone-breast-implant exposure data in 1992. RESULTS: ANA was positive (> or = 1:40) in 14% of women with silicone breast implants compared with 20% of healthy women (P = 0.11). Rheumatoid factor was positive (> or = 1:40) in 5% of women with silicone breast implants and 2% of healthy women (P = 0.16). Women with silicone breast implants had a significantly higher frequency of anti-ssDNA antibodies than healthy women (41% and 29%, P = 0.012). Duration of implant was associated with a higher frequency of anti-ssDNA antibodies (P = 0.03) but not with ANA or rheumatoid factor. No other significant differences in the frequencies of autoantibodies were observed in silicone breast implant-exposed women. Antisilicone antibodies were not found in any sample. CONCLUSION: We found no increased frequency of any immunologic abnormalities in women exposed to silicone breast implants, except for anti-ssDNA, which has unknown clinical relevance.

Adult↗
PubMed1999

The natural history of exercise-induced anaphylaxis: survey results from a 10-year follow-up study.

BACKGROUND: Exercise-induced anaphylaxis (EIA) is a unique physical allergy that is triggered by exertion, the clinical spectrum and modifying factors of which have been previously studied. At the time of initial description, it was postulated that other factors contributed to this disorder. OBJECTIVE: We sought to determine the clinical course and potential modifying factors in EIA. METHODS: In 1993, we conducted a cross-sectional analysis of 671 individuals with exercise-associated symptoms for more than a decade using a validated 75-item questionnaire. Subjects met criteria for EIA if they had anaphylactic symptoms, including hypotension or upper airway obstruction, urticaria, or angioedema with physical exertion but without a passive increase in core body temperature. RESULTS: Of 365 (54%) questionnaire respondents, 279 (87%) met criteria for EIA (199 females and 80 males). At the time of study entry, subjects with EIA (mean age, 37.5 years; range, 13 to 77 years) had an average of 10.6 years of symptoms, which were most frequently triggered by aerobic activities such as jogging or brisk walking (78% and 42%, respectively). On average, subjects reported that the frequency of attacks had decreased (47% of subjects) or stabilized (46% of subjects) since onset. One hundred (41%) subjects reported being completely free of attacks in the past year. Subjects reduced their attacks by avoiding exercise during extremely hot or cold weather (44%), avoiding ingestion of certain foods before exercise (37%), and restricting exercise during their allergy season (36%) or humid weather (33%). The most common pharmacologic agents used to manage symptoms were H1 antagonists (56%) and/or epinephrine (31%). However, 28% used no treatment at all. CONCLUSION: EIA is an episodic condition in which the frequency of attacks tends to stabilize or decrease over time. Improvement appears to result from individual modification of exercise and avoidance of known environmental and ingestible precipitants.

Adolescent↗
PubMed1999

Discrepancies between self-reported and observed physical function in the elderly: the influence of response shift and other factors.

GOAL: To explore the influence of social, psychological, and health factors on self-report of function. SUBJECTS: A convenience sample of 289 community-dwelling elderly aged 65-97 years. METHODS: We compared a measure of function based on observed performance, the Physical Capacity Evaluation (PCE) with a self-reported measure of functional limitations (HAQ), in a cross-sectional study. Stepwise multiple regression identified variables predicting self-reported disability, controlling for observed function. RESULTS: Controlling for PCE, self-reports of greater disability (HAQ) were predicted by current joint pain or stiffness, use of prescription medications, urban dwelling, depression, female gender, lack of memory problems, arthritis and lack of exercise. A final model included recent decline in function, dissatisfaction with function, gender, joint pain or stiffness, and observed function, explaining 85% of the variance in self-reported disability. The hypothesis that aging is associated with declining expectations of functional ability was not supported. However, recent health problems affected participants' reporting of limitations, consistent with a recalibration-type response shift. Perceived decline in function over the past six months, a fall within the last month, illness in the last week and pain or stiffness on the day of the exam all raised self-reports of disability. As suggested by adaptation level theory, subjects with recent problems might have an inflated perception of limitations due to shifts in their internal standards. When administered first, the observed performance test improved correlations between observed and self-reported function, primarily among those who did not report a recent decline in function. This suggests that this group may have benefited more from salient information about their abilities provided by performing the PCE before self-report. CONCLUSION: Our data confirm the importance of social, psychological, and health influences in self-report of disability, and are consistent with the hypothesis that people may recalibrate their self assessments based on recent health problems.

Aged↗
PubMed1999

Evaluation of recent clinical trials in lupus.

Clinical trials in lupus pose many challenges, ranging from small numbers of subjects to endpoints that are difficult to quantify. Improved standardization of both design and appropriate endpoints is necessary. Recent trials have been small in number, with few randomized controlled trials. These trials have evaluated therapies such as methotrexate, cyclosporine A, bromocriptine, immunoadsorption columns, and hydroxychloroquine withdrawal. With the advent of improved techniques as well as newer therapeutic agents, options for the treatment of lupus should begin to grow over the next several years in a fashion similar to that which has been seen in rheumatoid arthritis.

Clinical Trials as Topic↗
PubMed1999

Stable maintenance of linear bovine papillomavirus 1 molecules in C127I cells.

This paper describes the characterization of cell lines that stably maintain linear copies of bovine papillomavirus 1 (BPV-1). Cell lines were generated by liposome-mediated transfection of BamH1-linearized virus into C127I cells. Two transfectants with morphologies differing from each other and from that of the parental cell line were characterized. Southern blots indicated that they contain ten to twelve copies of the BPV-1 genome per cell and that the predominant species in both cell lines are linear BPV-1 episomes. One to two copies per genome of a slow migrating species are also present. Both BPV-1 species found in these cells are sensitive to BAL31 digestion. Viral chromosomal ends were amplified by anchored PCR, cloned and sequenced. Our results indicate that no major rearrangements have occurred in the sequence flanking the BamH1 site where the virus used for transfection was linearized. No circular BPV-1 molecules were detected by PCR. The slow migrating species may serve as templates for replication for the linear forms by a yet unidentified mechanism.

Animals↗
PubMed1998

Techniques to improve physicians' use of diagnostic tests: a new conceptual framework.

OBJECTIVES: To review the published literature on interventions aimed at improving physicians' testing practices and propose methodologic standards for these studies and to review selected studies using the PRECEDE framework, a behavioral model that helps categorize interventions based on which behavioral factors are being affected. DATA SOURCES: MEDLINE, EMBASE, and HEALTHStar databases were searched for the years 1966 to January 1, 1998, for English-language articles pertaining to diagnostic testing behavior; bibliographies were scanned to identify articles of potential interest; and researchers in health services, health behavior, and behavior modification were contacted for proprietary and other unpublished articles. STUDY SELECTION: A total of 102 articles were identified that described the results of interventions aimed at changing physicians' testing practices. We included the 49 studies that compared diagnostic testing practices in intervention and control groups. DATA EXTRACTION: Two investigators independently reviewed each article in a blinded fashion using a standard data collection form to obtain a methodologic score and to abstract the key elements of each intervention. DATA SYNTHESIS: On a 38-point methodologic criteria scale, the mean +/- SD score was 13+/-4.4. The desired behavior change was reported in the intervention group in 37 (76%) of 49 studies. Twenty-four (86%) of 28 interventions targeted at many behavioral factors were successful, while 13 (62%) of 21 studies aimed at a single behavioral factor were successful (P=.12). CONCLUSIONS: A majority of interventions to improve physicians' testing practices reported in the literature claimed success, with interventions based on multiple behavioral factors trending toward being more successful. While methodologic flaws hamper drawing strong conclusions from this literature, application of a behavioral framework appears to be useful in explaining interventions that are successful and can facilitate interpretation of intervention results.

Clinical Laboratory Techniques↗
PubMed1998

Yield of mtDNA mutation analysis in 2,000 patients.

The multiplex polymerase chain reaction-allele specific oligonucleotides (PCR/ASO) dot blot hybridization method was used to detect 44 mitochondrial DNA point mutations in 2,000 patients suspected as having mitochondrial DNA disorders. These point mutations are classified into four categories. Category I consists of primary disease-causing, heteroplasmic point mutations. Homoplasmic nucleotide substitutions that have been reported to be possibly disease associated are in Category II. Homoplasmic nucleotide substitutions that are thought to be benign polymorphism are included in category III. The novel nucleotide substitutions recently discovered in our laboratory by single strand conformation polymorphism analysis are in category IV. Frequencies of these 44 nucleotide substitutions in 2,000 patients and 262 control individuals were studied. The results indicated that analysis of 12 recurrent disease-causing point mutations in category I identified 5.4% of the patients suspected as having mitochondrial DNA disorders. Since the mitochondrial disorders are a group of complex, heterogeneous, and multisystemic diseases, it is often difficult to confirm clinical diagnosis without molecular studies. Thus, the multiplex PCR/ASO method is an effective approach for initial screening of mtDNA mutations in patients suspected as having mitochondrial DNA disorders.

DNA Mutational Analysis↗
PubMed1998

Lack of cardiac manifestations among patients with previously treated Lyme disease.

BACKGROUND: Cardiac involvement is common in acute Lyme disease, and case reports suggest that cardiac abnormalities might also occur years after the primary infection. OBJECTIVE: To determine the prevalence of cardiac abnormalities in persons with previously treated Lyme disease. DESIGN: Population-based, retrospective cohort study with controls. SETTING: Nantucket Island, Massachusetts. PARTICIPANTS: From among 3703 adult respondents to a total-population (n = 6046) mail survey, 336 (176 case-patients and 160 controls) were randomly selected for clinical evaluation. MEASUREMENTS: Current cardiac symptoms and major or minor abnormal electrocardiographic features, including heart rate; rhythm; axis; PR, QRS, and QT intervals; QRS structure; atrioventricular blocks; and ST-segment and T-wave changes. RESULTS: Persons with Lyme disease (case-patients, n = 176) (mean duration from disease onset to study evaluation, 5.2 years) and persons without evidence of previous Lyme disease (controls, n = 160) did not differ significantly in their patterns of current cardiac symptoms and electrocardiographic findings, including heart rate (P > 0.2), PR interval (P = 0.15), QRS interval (P > 0.2), QT interval (P > 0.2), axis (P > 0.2), presence of arrhythmias (P > 0.2), first-degree heart block (P = 0.12), bundle-branch block (P > 0.2), and ST-segment abnormalities (P > 0.2). In multivariate analyses that adjusted for age, sex, and previous heart disease, a history of previously treated Lyme disease was not associated with either major (odds ratio, 0.78; P > 0.2) or minor (odds ratio, 1.09; P > 0.2) electrocardiographic abnormalities. CONCLUSION: Persons with a history of previously treated Lyme disease do not have a higher prevalence of cardiac abnormalities than persons without a history of Lyme disease.

Adult↗
PubMed1998

Estimates of the prevalence of arthritis and selected musculoskeletal disorders in the United States.

OBJECTIVE: To provide a single source for the best available estimates of the national prevalence of arthritis in general and of selected musculoskeletal disorders (osteoarthritis, rheumatoid arthritis, juvenile rheumatoid arthritis, the spondylarthropathies, systemic lupus erythematosus, scleroderma, polymyalgia rheumatica/giant cell arteritis, gout, fibromyalgia, and low back pain). METHODS: The National Arthritis Data Workgroup reviewed data from available surveys, such as the National Health and Nutrition Examination Survey series. For overall national estimates, we used surveys based on representative samples. Because data based on national population samples are unavailable for most specific musculoskeletal conditions, we derived data from various smaller survey samples from defined populations. Prevalence estimates from these surveys were linked to 1990 US Bureau of the Census population data to calculate national estimates. We also estimated the expected frequency of arthritis in the year 2020. RESULTS: Current national estimates are provided, with important caveats regarding their interpretation, for self-reported arthritis and selected conditions. An estimated 15% (40 million) of Americans had some form of arthritis in 1995. By the year 2020, an estimated 18.2% (59.4 million) will be affected. CONCLUSION: Given the limitations of the data on which they are based, this report provides the best available prevalence estimates for arthritis and other rheumatic conditions overall, and for selected musculoskeletal disorders, in the US population.

Adolescent↗
PubMed1998

Preoperative education for total hip and knee replacement patients.

OBJECTIVE: Psychoeducational preparation is known to improve postoperative outcome. We tested two common psychoeducational procedures in elderly orthopedic patients, examining how best to match interventions to patients by psychological type. METHODS: Two hundred twenty-two elderly patients undergoing total hip or knee replacement were randomly assigned to 1) a slide-tape with information on the postoperative, in-hospital rehabilitation experience, or 2) training in Benson's Relaxation Response with a bedside audiotape, in a 2 x 2 factorial design. RESULTS: The relaxation response did not influence postoperative outcomes. The educational intervention reduced length of stay and pain medication use for patients who exhibited most denial (tendency to avoid thinking about unpleasant events), and reduced postoperative anxiety and cognitive errors on the Mini-Mental State Exam for patients with most baseline anxiety. There was no effect on postoperative pain. CONCLUSIONS: The importance of attending to the patient's psychological state and level of preparation before orthopedic surgery is reinforced. Patients who exhibit most denial and highest anxiety may benefit from educational interventions, but patients' directly expressing desire for information may be a poor guide in deciding which patients would benefit, compared with more formal psychological testing for denial and anxiety.

Aged↗
PubMed1998

3849 + 10 kb C --> T splicing mutation in Hispanic CF patients.

Seven patients compound heterozygous for the 3849 + 10kb C --> T mutation in the CFTR gene were found among the 152 patients attending the CHLA CF Clinic. The frequency of this mutation accounts for 2.3 and 3.9% of thetotal and Hispanic CF alleles of CHLA patients. These are significantly higher than the 0.6% of the general CF population. The average age of diagnosis of this group of Hispanics is 3.1 years, which is much younger than that reported for CF patients of other ethnicities with the same mutation. Both pancreatic sufficient and pancreatic insufficient patients were observed. It is concluded that the 3849 + 10kb C --> T mutation is associated with a variable but potentially mild type of CF.

Adult↗
PubMed1998

Linkage disequilibrium and linkage analysis of the glucose-6-phosphatase gene.

Recent studies have indicated that the four most common mutations account for 78% of mutant alleles in the glucose-6-phosphatase (G6Pase) gene. A significant fraction of mutant alleles remain unidentified. Thus, informative polymorphic markers are necessary for linkage analysis in carrier testing and prenatal diagnosis in families where mutations can not be identified. The common mutations appear to be ethnic-specific, suggesting that the individual mutations may have a common founder. With the recent discovery of the nucleotide 1176 polymorphism, we have studied whether these mutations are in linkage disequilibrium with the polymorphism. The results of polymerase chain reaction/allele-specific oligonucleotide analysis show that nucleotide 1 176 C is in linkage disequilibrium with mutations R83 C and R83H, and with the splicing mutation 727G-->T. The 1176T polymorphism is in linkage disequilibrium with 459insTA. A GT repeat polymorphism has also been found. However, its heterozygosity is low. The 1176 nucleotide polymorphic marker can be used in carrier and prenatal diagnosis of GSD1a families that have unidentified mutations and are informative for this marker.

Female↗
PubMed1998

Utilization of rheumatology physician services by the elderly.

PURPOSE: To examine rheumatology subspecialty practice patterns, determinants of referral to rheumatologists, and utilization of aspiration and injection procedures in a population-based sample of elderly individuals. SUBJECTS AND METHODS: We obtained Medicare physician claims for all visits to rheumatologists among beneficiaries aged 65 years and older in Colorado, Massachusetts, and Virginia in 1993, and for visits to all providers by patients with coded diagnoses of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). We examined variations in visit frequency and aspiration/injection procedures, and we analyzed determinants of referral to a rheumatologist for RA or SLE. RESULTS: In 1 year, 144,797 visits were made to rheumatologists by 38,443 patients in the three states. An inflammatory disorder was coded in 45% of visits and a noninflammatory disorder in 50%. Half of patients with RA were seen three or fewer times in the year. For RA and SLE, African Americans were about 60% as likely to be seen by a rheumatologist as whites. Utilization of rheumatologist services for rheumatoid arthritis and systemic lupus erythematosus was highest in the state (Virginia) with the lowest per capita supply of rheumatologists. Among patients with bursitis, tendinitis, and osteoarthritis, African-American women were more likely to receive an injection or aspiration procedure than whites or African-American men. CONCLUSION: Elderly patients with rheumatologic disorders were seen by specialists less frequently than recommended by a recent rheumatology manpower survey. African-Americans with RA and SLE had fewer rheumatology visits than whites.

Aged↗