Biomedical subjects

A Wilcox

Publications and source records attributed to A Wilcox.

At least 19 recordsLinked to original sources

PubMed2001

Spiral computed tomography for the diagnosis of pulmonary embolism in critically ill surgical patients: a comparison with pulmonary angiography.

HYPOTHESIS: Spiral computed tomographic pulmonary angiography (CTPA) is sensitive and specific in diagnosing pulmonary embolism (PE) in critically ill surgical patients. DESIGN: Prospective study comparing CTPA with the criterion standard, pulmonary angiography (PA). SETTING: Surgical intensive care unit of an academic hospital. PATIENTS: Twenty-two critically ill surgical patients with clinical suspicion of PE. The CTPAs and PAs were independently read by 4 radiologists (2 for each test) blinded to each other's interpretation. Clinical suspicion was classified as high, intermediate, or low according to predetermined criteria. All but 2 patients had marked pulmonary parenchymal disease at the time of the event that triggered evaluation for PE. INTERVENTIONS: Computed tomographic pulmonary angiography and PA in 22 patients, venous duplex scan in 19. RESULTS: Eleven patients (50%) had evidence of PE on PA, 5 in central and 6 in peripheral pulmonary arteries. The sensitivity and specificity of CTPA was, respectively, 45% and 82% for all PEs, 60% and 100% for central PEs, and 33% and 82% for peripheral PEs. Duplex scanning was 40% sensitive and 100% specific in diagnosing PE. The independent reviewers disagreed only in 14% of CTPA and 14% of PA interpretations. There were no differences in risk factors or clinical characteristics between patients with and without PE. The level of clinical suspicion was identical in the 2 groups. CONCLUSIONS: Pulmonary angiography remains the gold standard for the diagnosis of PE in critically ill surgical patients. Computed tomographic pulmonary angiography needs further evaluation in this population.

Adult↗

PubMed2001

The effect of the herbicide glyphosate on non-target spiders: Part I. Direct effects on Lepthyphantes tenuis under laboratory conditions.

We examined the toxic effects of glyphosate to adult female Lepthyphantes tenuis (Araneae, Linyphiidae), a common spider of agricultural habitats. The overspray technique was used to investigate the effect of the herbicide on forty individuals in each of six glyphosate treatments (2160, 1440, 1080, 720, 360 and 180 g ha-1) and a distilled water control. Spiders collected from the wild were individually placed in exposure chambers and checked every 24 h over a 72-h experimental period. Mortality of L tenuis remained at less than 10% in all treatments at 24 and 48 h after spray application, and only increased marginally (to 13%) after 72 h. These results support other limited data which suggest that glyphosate is 'harmless' to non-target arthropods. More extended laboratory testing to investigate any side-effects of glyphosate on the life history of L tenuis and other non-beneficial invertebrates is required.

Animals↗

PubMed2001

The effect of the herbicide glyphosate on non-target spiders: Part II. Indirect effects on Lepthyphantes tenuis in field margins.

We have examined the indirect effect of the herbicide glyphosate on the spider Lepthyphantes tenuis in field margins. Glyphosate was applied to a randomised block design field experiment comprising 360, 720 and 1440 g glyphosate AE ha-1 treatments and an unsprayed control. Spiders were sampled in each month from June to October 1998. Spider abundance was significantly lower in all the treatments than in the unsprayed control. Abundance was also significantly lower in the 720 and 1440 g treatments than in the 360 g treatment. No significant difference could be detected between the 720 and 1440 g treatments. Poisson regression models showed that patterns of decline in L tenuis were related to increasing dead vegetation and decreasing vegetation height. Glyphosate applications only had a within-season indirect habitat effect on L tenuis as field margins sprayed 16 months after an application of 360 g glyphosate ha-1 showed no detrimental effect.

Agriculture↗

PubMed2001

Evaluation of PCR, IEF and ELISA techniques for the detection and identification of potato cyst nematodes from field soil samples in England and Wales.

Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4-6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given.

Animals↗

PubMed2001

Effects of an aerobic exercise program on median nerve conduction and symptoms associated with carpal tunnel syndrome.

Carpal tunnel syndrome is associated with greater body mass index and less physical activity. To determine the effect of aerobic exercise on median nerve conduction and symptoms suggestive of carpal tunnel syndrome, 30 symptomatic volunteers (30 to 64 years old) with abnormal median nerve conduction studies participated in a 10-month program of supervised aerobic exercise. Changes in percentage of body fat, body mass index, peak oxygen consumption, 14-cm median sensory latency, and hand/wrist symptoms were assessed. A decrease in 14-cm sensory median latency correlated with a decrease in percentage of body fat (R = 0.52, P = 0.004) and was predicted by an increase in peak oxygen utilization (partial R = 0.52, P = 0.005) and a decrease in body mass index (partial R = 0.47, P = 0.014). There was also a tendency for a set of symptoms sometimes associated with carpal tunnel syndrome (pain, tightness, and clumsiness) to be relieved by the exercise program. These results suggest that an aerobic exercise program can be beneficial to median nerve function and may be associated with a reduction in hand symptoms.

Adult↗

PubMed2001

Handedness in boys with gender identity disorder.

Handedness preference was assessed in 205 boys with gender identity disorder and 205 clinical control boys referred for other reasons. Boys with gender identity disorder were significantly more likely to be left-handed than the clinical control boys (19.5% vs. 8.3%, respectively). The boys with gender identity disorder, but not the clinical control boys, also had a significantly higher rate of left-handedness compared to three independent, general population studies of nonreferred boys (11.8%; N = 14,253) by Hardyck, Goldman, and Petrinovich (1975), Calnan and Richardson (1976), and Eaton, Chipperfield, Ritchot, and Kostiuk (1996). Left-handedness appears to be a behavioral marker of an underlying neurobiological process associated with gender identity disorder in boys.

Child↗

PubMed2001

Around-the-clock attending radiology coverage is essential to avoid mistakes in the care of trauma patients.

Financial constraints due to increasing operating cost and decreased reimbursement do not allow many hospitals to maintain coverage by attending radiologists around the clock (CARAC). Preliminary film readings by radiology trainees may be inaccurate. In trauma, decisions are made fast and are often based on these preliminary readings. To examine whether there are significant discrepancies between preliminary readings (PRs) and final readings (FRs) of CT scans of trauma patients we prospectively recorded PRs (done immediately by radiology residents) and FRs (done the following working day by radiology attendings) over a period of 6 months for trauma CT scans done between 5 PM and 7 AM on weekdays or weekends. A discrepancy was classified as significant if a change in management was instituted after FR. In 42 of 383 (11%) trauma patients there was a discrepancy between PR and FR. Patients with discrepancies had a higher Injury Severity Score, higher incidence of penetrating trauma, longer hospital stay, higher hospital charges, and higher mortality than patients without any discrepancy. Most of the discrepancies were found on abdominal CT scans. The lower the level of radiology resident doing the PR the higher the likelihood of a discrepancy. In 20 patients (5%) a significant discrepancy was found. We conclude that the absence of CARAC results in inaccurate FRs risking optimal trauma patient care. The institutional savings realized by avoiding CARAC may be offset by the cost of additional care provided to patients who have delayed diagnosis and treatment due to the lack of it.

Adult↗

PubMed2000

Why do Mexican Americans give birth to few low-birth-weight infants?

There are relatively few low-weight births among Mexican Americans, despite their socioeconomic disadvantages. Fewer low-birth-weight (LBW) births result when babies are heavier at term or when there are fewer preterm deliveries. The authors used 1994 US singleton livebirth birth certificates to compare Mexican Americans with non-Hispanic Whites. They found that the lower LBW rate among Mexican Americans (5.8%) compared with non-Hispanic Whites (6.1%) occurred because fewer small, preterm babies were born to Mexican Americans (3.4% vs. 3.9%). This result was obscured by two findings. First, the mean birth weight of Mexican American babies (3,343 g) was lower than that of non-Hispanic White babies (3,393 g). This finding again showed the independence of mean birth weight and LBW. Second, the overall preterm birth rate was higher among Mexican Americans (10.6%) than non-Hispanic Whites (9.3%). Our hypothesis is that this finding reflects errors in recorded gestational age, as illustrated by a strongly bimodal birth-weight distribution at young gestational ages for Mexican Americans. Further studies on the LBW paradox among Mexican Americans should thus focus on gestational age more than on birth weight.

Adolescent↗

PubMed2000

A European pest to control a new zealand weed: investigating the safety of heather beetle, Lochmaea suturalis (Coleoptera: Chrysomelidae) for biological control of heather, Calluna vulgaris.

Heather, Calluna vulgaris (L.) Hull, is a serious invasive weed in the central North Island of New Zealand, especially in Tongariro National Park, a World Heritage Area. Heather beetle, Lochmaea suturalis (Thomson), is a foliage-feeding pest of Calluna in Europe, that was selected as the most promising biological control agent for introduction into New Zealand, because it causes high levels of damage to Calluna in Europe. Host-range tests indicated that L. suturalis poses a negligible threat to native New Zealand plants. Cultivars of Calluna grown as ornamentals are suitable food plants, but are unlikely to be severely affected because L. suturalis requires a damp understorey of moss or litter for successful oviposition and pupation, which is rarely present in gardens. However, mosses and litter occurring under Calluna stands in Tongariro National Park are suitable substrates for eggs and pupae. Lochmaea suturalis released in New Zealand has been freed of parasitoids and a microsporidian disease that attack the beetles in Europe.

Animals↗

PubMed2000

Bone sarcoidosis.

Sarcoidosis is a disease that exhibits extremely heterogeneous clinical manifestations. Although the lungs are the most commonly involved organs, the extension of the granulomatous process may also affect the bones. Almost any bone can be involved; curiously, the small bones of the hands and feet are most frequently affected. Diagnosis and recognition of osseous sarcoidosis is easy, but the therapy is disappointing. Corticosteroids and antimalarials may control pain and swelling, but usually do not influence the course of osseous sarcoidosis.

Antimalarials↗

PubMed2000

Medical text representations for inductive learning.

Inductive learning algorithms have been proposed as methods for classifying medical text reports. Many of these proposed techniques differ in the way the text is represented for use by the learning algorithms. Slight differences can occur between representations that may be chosen arbitrarily, but such differences can significantly affect classification algorithm performance. We examined 8 different data representation techniques used for medical text, and evaluated their use with standard machine learning algorithms. We measured the loss of classification-relevant information due to each representation. Representations that captured status information explicitly resulted in significantly better performance. Algorithm performance was dependent on subtle differences in data representation.

Algorithms↗

PubMed1999

Classification algorithms applied to narrative reports.

Narrative text reports represent a significant source of clinical data. However, the information stored in these reports is inaccessible to many automated decision support systems. Data mining techniques can assist in extracting information from narrative data. Multiple classification methods, such as rule generation, decision trees, Bayesian classifiers, and information retrieval were used to classify a set of 200 chest X-ray reports according to 6 clinical conditions indicated. A general-purpose natural language processor was used to convert the narrative text into a coded form that could be used by the classification algorithms. Significant differences in performance were found between algorithms. The best performing algorithm applied to the processor output was significantly better than information retrieval applied to raw text. Predictor variables from the coded processor output were limited to avoid overfitting. Methods that limited by domain knowledge performed significantly better than those that limited by conditional probabilities of the variables in the training set. Algorithms were also shown to be dependent on training set size.

Algorithms↗

PubMed1998

Developing online support for clinical information system developers: the FAQ approach.

OBJECTIVE: We investigate a knowledge-based help system for developers of an integrated clinical information system (CIS). The first objective in the study was to determine the system's ability to answer users' questions effectively. User performance and behavior were studied. The second objective was to evaluate the effect of using questions and answers to augment or replace traditional program documentation. DESIGN: A comparative study of user and system effectiveness using a collection of 47 veritable questions regarding the CIS, solicited from various CIS developers, is conducted. Most questions were concerning the clinical data model and acquiring the data. MEASUREMENTS: Answers using current documentation known by users were compared to answers found using the help system. Answers existing within traditional documentation were compared to answers existing within question-answer exchanges (Q-A's). RESULTS: The support system augmented 39% of users' answers to test questions. Though the Q-A's were less than 5% of the total documentation collected, these files contained answers to nearly 50% of the questions in the test group. The rest of the documentation contained about 75% of the answers. CONCLUSIONS: A knowledge-based help system built by collecting questions and answers can be a viable alternative to large documentation files, providing the questions and answers can be collected effectively.

Artificial Intelligence↗

PubMed1998

Knowledge discovery and data mining to assist natural language understanding.

As natural language processing systems become more frequent in clinical use, methods for interpreting the output of these programs become increasingly important. These methods require the effort of a domain expert, who must build specific queries and rules for interpreting the processor output. Knowledge discovery and data mining tools can be used instead of a domain expert to automatically generate these queries and rules. C5.0, a decision tree generator, was used to create a rule base for a natural language understanding system. A general-purpose natural language processor using this rule base was tested on a set of 200 chest radiograph reports. When a small set of reports, classified by physicians, was used as the training set, the generated rule base performed as well as lay persons, but worse than physicians. When a larger set of reports, using ICD9 coding to classify the set, was used for training the system, the rule base performed worse than the physicians and lay persons. It appears that a larger, more accurate training set is needed to increase performance of the method.

Artificial Intelligence↗

PubMed1997

Genomic structure and chromosomal localization of a human myo-inositol monophosphatase gene (IMPA).

Manic-depressive illness is a serious psychiatric disorder that in many, but far from all, patients can be treated with lithium. The main causes for discontinuation of lithium therapy are unpleasant or serious side effects and lack of response. The reason for the striking variation in clinical efficacy of lithium treatment among bipolar patients is not known. The enzyme myo-inositol monophosphatase (IMPase) has been postulated as a target for the mood-stabilizing effects of lithium, but variation in the coding region of the human IMPA gene encoding IMPase activity has not been observed in manic-depressive patients (Steen et al., Pharmacogenetics, 1996, 6, 113-116). It is nevertheless conceivable that polymorphisms or mutations in the noncoding regions of this gene could influence the lithium response in psychiatric patients. As a first step in investigating this possibility, we here report the genomic structure of the human IMPA gene. The gene is composed of at least nine exons and covers more than 20 kb of sequence on chromosome 8q21.13-q21.3. In the 3'-untranslated part of the gene, we observed a polymorphism (a G to A transition) and also two short sequences similar to the inositol/cholin-responsive element consensus. Finally, we postulate that two additional IMPA-like transcripts originate from the human genome, one from a position close to IMPA itself on chromosome 8 and the other from chromosome 18p. Our data may contribute to the identification of genetic factors involved in the pathogenesis and determination of treatment response in manic-depressive illness.

Amino Acid Sequence↗

PubMed1997

The effect of substrate utilization, manipulated by nicotinic acid, on excess postexercise oxygen consumption.

Increased fat oxidation during the recovery period from exercise is thought to be a contributing factor for excess postexercise oxygen consumption (EPOC). In an attempt to study the effect of serum free fatty acid (FFA) availability during exercise and recovery on the EPOC, nicotinic acid, a potent inhibitor of FFA mobilization from adipose tissue, was administered to five trained male cyclists prior to, during, and after a bout of cycling at 65% VO2max. In the nicotinic acid trial, a 500 mg dose of nicotinic acid was ingested prior to exercise, and 100 mg doses were ingested at 15, 30, and 45 min exercise, and 30 min recovery. The cyclists also completed a trial under control conditions. Serum FFA, serum glycerol, RER and VO2 were monitored during rest, exercise, and recovery, each of which was 1-h in duration. Nicotinic acid ingestion prevented the increase in serum FFA that occurred during exercise in the control trial. FFA levels during the nicotinic acid trial were significantly lower than control values during both exercise and recovery. Serum glycerol levels were also significantly lower during exercise in the nicotinic acid trial, indicative of a reduction in lipolysis. RER was not significantly different at rest or during exercise; however, RER values were significantly lower during recovery in the control trial, indicative of greater fat oxidation. For both treatments, postexercise VO2 remained elevated above resting levels at the completion of the 1-h recovery period. However, the magnitude of EPOC was significantly reduced after FFA blockade with nicotinic acid (3.4 +/- 0.61 vs 5.5 +/- 0.71). These results support the hypothesis that increased FFA metabolism during exercise and recovery is an important contributing factor to the magnitude of EPOC.

Adipose Tissue↗

PubMed1997

Creating an environment for linking knowledge-based systems to a clinical database: a suite of tools.

A difficulty in using knowledge-based systems has been linking them to clinical databases. The challenge is in making a correct mapping from the data in the knowledge base to the data in the database. At Columbia-Presbyterian Medical Center, we have built a suite of tools developed to create queries that address this challenge. The tools were designed to allow users to easily retrieve data from the database without requiring the users have extensive database and vocabulary knowledge. The tools help users write correct queries (Query Builder), find correct terms in the clinical database (MED Browser), aggregate the resulting data into a useful form (Clinical Database Browser), and allow the user to test the query within the environment of the knowledge-based system (Event Playback). The tools have been in use for one year.

Artificial Intelligence↗

PubMed1996

Comparison of methods of assessing vitamin A status in children.

OBJECTIVE: A study of children (2-8 years; n = 613) in Belize, Central America, was conducted to determine what proportion of the children might be at risk of vitamin A (vit A) deficiency. The data provide an opportunity to compare results of three methods of assessing vit A status in a population which was not severely malnourished. Serum retinyl ester concentrations were also determined; their relevance to one of the tests, the relative dose response (RDR) test, is discussed. METHODS: The three methods of assessing vit A status were: RDR test, fasting serum retinol concentration, and conjunctival impression cytology (CIC). Retinol-binding protein (RBP), serum retinyl esters and serum zinc concentrations were also determined. RESULTS: Inadequate vit A status was indicated for 17% of subjects by the RDR test (14% cutoff), for 24% by fasting serum retinol concentration (< 0.87 mumol/L), and for 49% by "abnormal" CIC score. Retinyl esters constituted 24% of serum retinoids at the time (5 hours after a retinyl palmitate dose) at which the second blood sample is taken for the RDR test. Regression tree analyses (CART) indicated ethnicity was a predictor of RDR score; ethnicity, stunting and age were predictors of fasting serum retinol concentration; ethnicity and stunting were predictors of 0-hour retinyl ester concentration. CONCLUSION: The three indices of vit A status did not identify the same individuals nor indicate the same percentage of the population to be at risk for vit A deficiency. Increased concentrations of retinyl esters at 5 hours compared to those at 0 hours suggest that insufficient retinol may have been taken up by the liver at 5 hours to release all accumulated retinol-binding protein (RBP) in deficient individuals; prevalence of vit A deficiency might therefore be underestimated by the RDR test. The selection of ethnicity as a predictor of RDR score and of 0-hour retinol and retinyl ester concentrations suggests that factors other than vit A status affect vit A metabolism and may affect the RDR test.

Belize↗