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Role of liver function tests in predicting common bile duct stones in acute calculous cholecystitis.

BACKGROUND: The role of liver function tests (LFTs) in evaluating common bile duct (CBD) stones in patients with cholelithiasis has been studied widely. However, it is not clear whether these predictive models are useful in inflammatory gallstone disease. METHODS: A review was undertaken of 385 consecutive patients admitted as an emergency for acute calculous gallbladder disease. The diagnosis of calculous cholecystitis was confirmed by ultrasonography or histological confirmation of acute or chronic inflammation of the gallbladder. Patients with obvious jaundice, defined as a bilirubin level above 80 micromol/l, and gallstone pancreatitis were excluded. RESULTS: Some 216 patients met the inclusion criteria, of whom 28 (13.0 per cent) were found to have CBD stones. LFT results were not significantly different in patients with chronic, acute or complicated acute cholecystitis. Using several cut-off levels, gamma-glutamyl transpeptidase (GGT) had the highest specificity, positive predictive value and negative predictive value, comparable to a scoring system that combined all LFTs. Bilirubin was the least specific and predictive. A cut-off point for GGT at 90 units/l produced a sensitivity of 86 per cent (24 of 28), specificity of 74.5 per cent (140 of 188), and positive and negative predictive values of 33 per cent (24 of 72) and 97.2 per cent (140 of 144) respectively. This represented a one in three chance of CBD stones when the GGT level was above 90 units/l and a one in 30 chance when the level was less than 90 units/l. CONCLUSION: Selection criteria based on GGT can be used in acute calculous cholecystitis to identify high-risk patients who would benefit most from further imaging to exclude choledocholithiasis.

Adolescent↗

Validity of the Medical College Admission Test for predicting medical school performance.

PURPOSE: Since the introduction of the revised Medical College Admission Test (MCAT(R)) in 1991, the Association of American Medical Colleges has been investigating the extent to which MCAT scores supplement the power of undergraduate grade point averages (uGPAs) to predict success in medical school. This report is a comprehensive summary of the relationships between MCAT scores and (1) medical school grades, (2) United States Medical Licensing Examination (USMLE) Step scores, and (3) academic distinction or difficulty. METHOD: This study followed two cohorts from entrance to medical school through residency. Students from 14 medical schools' 1992 and 1993 entering classes provided data for predicting medical school grades and academic difficulty/distinction, while their peers from all of the U.S. medical schools were used to predict performance on USMLE Steps 1, 2, and 3. Regression analyses assessed the predictive power of combinations of uGPAs, MCAT scores, and undergraduate-institution selectivity. RESULTS: Grades were best predicted by a combination of MCAT scores and uGPAs, with MCAT scores providing a substantial increment over uGPAs. MCAT scores were better predictors of USMLE Step scores than were uGPAs, and the combination did little better than MCAT scores alone. The probability of experiencing academic difficulty or distinction tended to vary with MCAT scores. MCAT scores were strong predictors of scores for all three Step examinations, particularly Step 1. CONCLUSIONS: MCAT scores almost double the proportion of variance in medical school grades explained by uGPAs, and essentially replace the need for uGPAs in their impressive prediction of Step scores. The MCAT performs well as an indicator of academic preparation for medical school, independent of the school-specific handicaps of uGPAs.

Clinical Competence↗

The diagnostic accuracy of rapid dipstick tests to predict urinary tract infection.

This study summarizes the diagnostic accuracy data for dipstick nitrite and/or leukocyte esterase tests (the index tests) as predictors of bacterial urinary tract infection as defined by quantitative culture (the reference test). On-line search of the literature using the MEDLARS database identified 1,017 citations, 51 of which were relevant and contained sufficient data for further analysis. From each citation, 2 x 2 tables of true-positive, true-negative, false-positive, and false-negative results were extracted. Four categories of index test were assessed: nitrite only, leukocyte esterase only, disjunctive pairing (dipstick positive if nitrite, leukocyte esterase, or both were positive), and conjunctive pairing (dipstick positive only if both nitrite and leukocyte esterase were positive). The true- and false-positive rates were calculated from each 2 x 2 table. Plots of true-positive rates versus false-positive rates demonstrated widely scattered points, indicating heterogeneity. A receiver-operating characteristic curve was fitted to the data using logistic transforms and weighted linear regression. This analysis revealed that the disjunctive pair is the most accurate index test. However, in many clinical settings, the posterior probability of urinary tract infection given a negative dipstick is too high to exclude it. Within most clinically relevant ranges of true- and false-positive rates, a negative urine dipstick test cannot exclude the diagnosis of urinary tract infection in patients with high prior probabilities of contracting this infection. For lower prior probabilities, the clinical efficacy of these rapid tests would best be determined by decision analysis, for which these receiver-operating characteristic functions would serve as valuable analytical tools.

Diagnostic Tests, Routine↗

Predictive and diagnostic tests of renal failure: a review.

Postoperative acute renal insufficiency is a discouraging complication with a mortality rate that remains persistently high, despite improved techniques of dialysis and advances in the perioperative management of hemodynamic, metabolic, and infective complications. A complete understanding of the role of renal hemodynamics in the pathophysiology of acute renal failure still has not emerged. Serial determination of creatinine clearance is currently the most sensitive test for predicting the onset of perioperative renal dysfunction; however, the test is not practical for measuring renal function under operating room conditions. Furthermore, testing creatinine clearance is time-consuming, labor intensive, and may cause significant delay in identifying the onset of renal dysfunction. That early therapy modifies the prognosis of renal dysfunction remains an untested hypothesis until a measurement that predicts renal outcome is found that is sensitive, specific, and easily obtainable. The ability to measure intrarenal blood flow distribution may offer promise for improving our predictive and diagnostic abilities to assess perioperative acute renal failure. Methodologic constraints, however, limit the practicality of this measurement in the perioperative setting at this time. Instead, we rely on indirect variables that do not bear a reliable relationship to glomerular filtration rate and renal function.

Acute Kidney Injury↗

Predictive animal testing for photocontact allergenicity.

The purpose of this investigation was to establish a standardized animal model to predict the photoallergenic potential of new chemical compounds. In a first series of experiments the main factors influencing the induction of photoallergenicity were evaluated (induction concentration, pH of the test solution, pretreatment of the irradiation site with sodium lauryl sulphate, additional use of adjuvant injections and routes of administration). Osram Ultravitalux lamps were utilized for these studies. In a second series of experiments a Xenon 6000 W radiation source was used. Positive results were obtained with well known photosensitizers, as, for instance, the halogenated salicylanilides, as well as with so-called weak photoallergens (e.g. bithionol, sulphanilamide) by stimulating the animals' immune system with Freund's complete adjuvant. The photoallergenic compounds were at the same time tested for their contact allergenic potential in the optimization test. A standard procedure for the predictive photoallergenicity assay in guinea-pigs is proposed.

Adjuvants, Immunologic↗

Use of an in vitro haemolysis test to predict tissue irritancy in an intramuscular formulation.

As part of a drug development program, an in vitro haemolysis test has been used to predict the in vivo muscle tissue irritancy of intramuscular (i.m.) formulations of a new drug entity. Solutions of lactic acid, polyvinylpyrrolidone (PVP) 12PF and two commercial injections were also included in the study. The results indicated that the test was able to differentiate formulations in terms of haemolytic potential and the correlation between the haemolysis test results and in vivo intramuscular irritancy studies indicated that the test may be used to screen formulations for potential tissue irritancy prior to in vivo evaluation.

Animal Testing Alternatives↗

Further characterization of the supine empty stress test for predicting low valsalva leak point pressures.

The aim of this study is to determine if the diagnostic accuracy of the supine empty stress test (SEST) differs depending on the volume of residual urine. We performed a review of all patients who were diagnosed with stress urinary incontinence (SUI) via multi-channel urodynamics including valsalva leak point determinations (VLPP). A SEST was performed and the residual urine recorded via catheterization. The test-specific indices of the SEST for the prediction of low VLPP (defined as <60 cm H(2)0) were determined for varying residual volumes. Ninety-nine patients were included. Regardless of residual volume, low sensitivities, specificities and positive predictive values were demonstrated. Sensitivity and positive predictive values were further reduced and negative predictive values were improved slightly with higher residual volume. The highest negative predictive value was 89% at a residual volume of greater than 10 mL. Residual urine volume has minimal impact on the utility of the SEST.

Female↗

Evaluation of the shake test to predict respiratory distress syndrome.

An analysis of the relationship of amniotic fluid shake test titers and the subsequent fetal lung maturity as evinced by the development of the respiratory distress syndrome (RDS) has been conducted. Over a four-year period, 131 amniotic fluid samples were tested within 48 hours of delivery. RDS was diagnosed in 16 infants. When the shake test was positive at a 1:2 dilution, one child developed a mild case of RDS (2.3%). If the test was postivie at a 1:4 dilution, none developed RDS. RDS occurred in 15% of the cases with a positive test at a 1:1 dilution and in 30% of the cases with a negative test. This test has proved to be an excellent screening method for predicting fetal lung maturity if it is positive at 1:2 or greater. If the result is positive at a 1:1 dilution, or negative, other methods must be used for assessment. Its advantages are its rapidity, simplicity, and low cost.

Amniotic Fluid↗

Predictive aspects of the abduction external rotation test among male industrial and office workers.

BACKGROUND: Nerve compression of the brachial plexus can be provoked by the Abduction External Rotation (AER) test where the arms are held in a "hands-up" position. METHODS: The AER test was conducted among 137 male industrial and office workers at baseline and after 5 years follow-up, together with a medical examination/history and exposure analysis. Nerve conduction measurements in the wrist regions were also made. RESULTS: The cumulated incidence of neurological signs during the AER test, was estimated to be 2/100 person-years. Factors related to work-conditions, constitution, disease, and neck trauma were associated with AER signs. Subjects with AER signs exhibited a slowing of the nerve conduction velocities in the wrist region. The AER test predicted future neck and upper extremity symptoms and signs of nerve compression. CONCLUSIONS: The results of this study gave support to the "double or multiple crush" theory of nerve compression. Prevention, evaluation, and management of neck and upper extremity nerve compression diseases should, therefore, attend to all probable locations of such compression, even when a specific location is in focus. The AER test can be a supplementary tool in such work, both in epidemiological and occupational health settings.

Adult↗

The efficacy of endocrine disruptor screening tests in detecting anti-estrogenic effects downstream of receptor-ligand interactions.

Several predictive test methods for endocrine disrupters have been evaluated by international organizations. In this study, we performed a series of predictive tests for endocrine disrupters, i.e. the receptor binding assay, reporter gene assay, and immature rat uterotrophic assay, on all-trans retinoic acid (tRA), which may cause antiestrogenic activity via their receptors, interfere with estrogenic action at estrogen responsive element level, and we examine the efficacy of endocrine disruptor screening tests in detecting anti-estrogenic effects downstream of receptor-ligand interactions. Despite showing complete lack of binding affinity to ER in the receptor binding assay, tRA exhibited clear antagonist activity without any agonist activity in the reporter gene assay. In the in vivo test, tRA was subcutaneously administered to immature Crj:CD (SD) IGS rats at doses of 5 and 25 mg/kg per day for 3 days, beginning at 20 days of age. Additional groups of rats given tRA at the above doses were also subcutaneously injected with ethinyl estradiol (EE) at a dose of 0.6 microg per rat per day. A vehicle control group given olive oil alone and a positive control group given EE alone were also established. Although no uterotrophic activity was detected in any of the rats given only tRA, co-treatment with 5 and 25 mg/kg tRA and EE reduced the EE-induced increases in uterine weight. We confirmed that the ER antagonist activity of tRA may be mediated by transcriptional interference after ER-ligand complex binding to an estrogen responsive element of the gene by the gel mobility shift analysis. These findings suggest the reporter gene assay and uterotrophic assay can detect anti-estrogenic effects downstream of receptor-ligand interactions, but the receptor binding assay can not detect this type of interference. In any case, a screening strategy for endocrine disrupters, especially the primary screening battery for prioritizing the chemicals to be tested in the higher screening stages, should be designed to detect various kinds of chemicals possessing endocrine modulating activity including a retinoid-like endocrine modulator. Accordingly, reporter gene assay or uterotrophic assay should be conducted in the early stage of screening process for endocrine disrupting chemicals, because they can detect antagonist activity caused by both inhibition of receptor-ligand interaction and transcriptional interference. Particularly, the reporter gene assay may be a promising prescreening procedure, because it can be adopted in the high throughput screening process for thousands of chemicals and it requires no use of experimental animals.

Animals↗

Allergy history does not predict skin test reactivity in asthmatic children.

We prospectively assessed how well patient report of allergy to cat, dust mite, and grass predicted the results of skin prick testing to those allergens in 95 asthmatic children. Children between 4 and 18 years old with physician-documented asthma provided a detailed standardized allergy history and then underwent skin prick testing. The children were categorized by asthma severity. The diagnostic accuracy, which was the primary outcome measure, as well as sensitivity, specificity, and positive and negative predicted values were calculated for allergy history with regards to skin test reactivity. The diagnostic accuracy of allergy history in identifying skin test reactivity was 65%, 50%, and 56% for cat, dust mite, and grass, respectively. Asthma severity did not affect the diagnostic accuracy. Allergy history was a poor predictor of skin test reactivity in this group of asthmatic children.

Adolescent↗

Predictive genetic testing to control coronary heart disease and hyperlipidemia.

The contribution of genes to the etiology of coronary heart disease (CHD) is highly significant even when monogenic hyperlipidemias are excluded. Previous studies in the area of quantitative genetics and of disease or risk factor association with random genetic markers have, in recent years, been supplemented with studies focused on "candidate genes"--genes whose products are known or suspected to be involved in the atherogenic process, the thrombogenic process, lipid metabolism, or apolipoprotein (apo) structure or function. In 1974, the candidate gene approach led to the detection of a strong association between genetically determined Lp(a) lipoprotein and premature CHD and, in 1976, also led to the detection, in several populations, of the association between lipid levels and genetic types in the normal low density lipoprotein (LDL) polymorphism referred to as the Ag(x) variation. Restriction fragment length polymorphisms in DNA have been uncovered in the genes for several functionally important proteins including apos. Some of these DNA variants have been reported to be associated with CHD or lipid level. Such variants should become useful tools in predictive genetic testing for CHD risk. Most studies on the genetics of risk factors have focused on risk factor level. Because an individual's propensity to develop atherosclerosis could depend not only on absolute lipid levels but also on lipid responses to atherogenic stimuli, we have developed a method to examine if "variability genes" exist. To detect the latter class of genes, we examine within-pair differences in quantitative parameters between monozygotic (MZ) twin pairs possessing and MZ twin pairs lacking the gene under study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

The value of the postcoital test in predicting the fertilization of human oocytes.

The relevance of the postcoital test (PCT) in relation to the fertilization rate of oocytes was determined in an analysis of 66 couples in an in vitro fertilization (IVF) program. The test is routinely performed in the workup of all IVF patients and is accurately timed to the immediate preovulatory period by daily hormonal, cervical mucus, and ultrasound monitoring. Cases demonstrating antispermatozoal antibodies in the serum of either partner, in cervical mucus, or in semen were excluded. There was no significant difference in the fertilization rate of oocytes whether the PCT result was negative, equivocal, or positive, and the finding was the same in both normospermic and oligospermic groups. It is concluded that the PCT is of no value in predicting the outcome of IVF and, conversely, IVF should be considered as a therapeutic option for couples with a negative PCT.

Antibodies↗

Clinical utility of cytomegalovirus viral load testing for predicting CMV disease in D+/R- solid organ transplant recipients.

Despite prophylaxis, cytomegalovirus (CMV) disease is common in donor seropositive (D+)/recipient seronegative (R-) transplant patients after cessation of prophylaxis. Early detection of CMV may allow for pre-emptive therapy to prevent active disease. The clinical utility of quantitative plasma viral load measurements for predicting CMV disease was determined in 364 D+/R- organ transplant patients receiving prophylaxis (100 d of valganciclovir or oral ganciclovir). Measurements were performed every 2 weeks until day 100 and at months 4, 4.5, 5, 6, 8 and 12 post-transplant. CMV disease occurred in 64 (17.6%) patients by 12 months. Using a positive cut-off value of >400 copies/mL, sensitivity was 38%, specificity 60%, positive predictive value 17%, and negative predictive value 82% for prediction of CMV disease. Therefore, routine monitoring would have predicted disease in only 24/64 (38%) patients. The test characteristics were not improved by changing the viral load cut-off point for defining a positive result. Similarly, single time point measures at the end of prophylaxis or month 4 had low sensitivity for disease prediction. Overall, regular CMV plasma viral load measurements were only of modest value in predicting CMV disease.

Administration, Oral↗

Short-term test for predicting the potential of xenobiotics to impair reproductive success in fish.

Short-term screening tests with the zebra fish (Brachydanio rerio) have been developed for predicting the potential of xenobiotics to impair reproductive success in fish. The aim was to find simple and sensitive test parameters and to simulate exposure situations typical for anadromous fish species (salmonids), which generally cross heavily polluted coastal areas or estuaries before they reach uncontaminated upstream spawning areas. Therefore, particular attention was directed to tests designed to assess adverse effects induced during gametogenesis in adult fish. the test protocol involves exposure of adults prior to, but not during, spawning and the effects are measured in the offspring as alterations in hatching frequency and hatching rate of eggs, and survival and stress tolerance of embryos and larvae. Some representative examples of the application of these tests are given, and it is shown that impairment of reproductive success can be induced by exposure of parent fish prior to spawning at concentrations of xenobiotics at least five times lower than those yielding effects during direct exposure of embryos and larvae. It is suggested that, in hazard assessment programs, tests of the effect of xenobiotics on the offspring of preexposed adults be routinely incorporated.

Animals↗

Implications of exercise testing for prediction of athletic performance: a contemporary perspective.

One of the most fundamental beliefs in exercise physiology is that performance during maximum exercise of short duration is limited by the inability of the heart and lungs to provide oxygen at a rate sufficiently fast to fuel energy production by the active muscle mass. This belief originates from work undertaken in the 1920's by Hill and Lupton. A result is that most, if not all, of the studies explaining the effects of exercise training or detraining or other interventions on human physiology explain these changes in terms either of central adaptations increasing oxygen delivery to muscle or of peripheral adaptations that modify the rates of oxygen or fuel utilization by the active muscles. Yet a critical review of Hill and Lupton's results shows that they inferred but certainly did not prove that oxygen limitation develops during maximal exercise. Furthermore, more modern studies suggest that, if such an oxygen limitation does indeed occur during maximal exercise, it develops in about 50% of test subjects. Thus, an alternative mechanism may need to be evoked to explain exhaustion during maximal exercise in a rather large group of subjects. This review proposes that the factors limiting maximal exercise performance might be better explained in terms of a failure of muscle contractility ("muscle power"), which may be independent of tissue oxygen deficiency. The implications for exercise testing and the prediction of athletic performance are discussed.

Energy Metabolism↗

Age-related physical fitness and the predictive values of fitness tests for work ability in home care work.

Despite the widespread assessment of physical fitness in occupational medicine and health services, only a few validity studies have been made of the fitness tests used in relation to job demands. The purpose of this study was to assess the physical fitness of female home care workers (n = 132) in relation to age and to evaluate whether the fitness tests used predict work ability over a 5-year period of follow-up. Muscle endurance declined by 18% to 37%, and isometric muscle strength by 10% to 18%, from the youngest (21 to 35 years) to the oldest (45 to 59 years) age group. The proportion of those subjects who could be classified below the average age-related fitness categories according to the maximal oxygen consumption was highest (50%) for the 21-to-35 age group. The logistic regression model showed that obesity (odds ratio [OR] = 7.51) and poor results on the sit-up (OR, 8.9), balance (OR, 6.5), and weight-lifting (OR, 4.6) tests predicted the highest risk for reduced work ability, according to the work ability index used in the 5-year follow-up. Moreover, average results for the trunk side-bending test (OR, 4.6), poor results for the squatting test (OR, 3.8), poor knee extension strength (OR, 4.2), and the average maximal oxygen consumption (l.min-1) (OR, 3.1) indicated a high risk for reduction in work ability. The physical fitness tests were strongly associated with the physical demands of home care work and were relevant for the evaluation of work-related fitness among home care workers.

Adult↗