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Biomedical subjects

J Martin

Publications and source records attributed to J Martin.

At least 271 records · Page 15Linked to original sources
PubMed1999

The attentional blink reflects retrieval competition among multiple rapid serial visual presentation items: tests of an interference model.

When people respond to a target (T1) in a rapid serial visual presentation stream, their perception of a subsequent target (T2) is impaired if the intertarget stimulus onset asynchrony is between about 100 and 500 ms. Three experiments supported the interference model's (K. L. Shapiro, J. E. Raymond, & K. M. Arnell, 1994) claim that this attentional blink reflects competition for retrieval among multiple items in visual short-term memory. Experiments 1 and 2 revealed that items appearing during the blink are named as T2 on an above-chance proportion of trials when T2 must be identified. Experiment 3 demonstrated that both the size of the blink and sensitivity to T2 reflected the number of items competing for retrieval as T2; such competition, moreover, occurred at a conceptual or categorical level rather than at a purely visual one. The relationship between the interference and alternative models of the attentional blink is discussed.

Adolescent↗
PubMed1999

An encyclopedia of mouse genes.

The laboratory mouse is the premier model system for studies of mammalian development due to the powerful classical genetic analysis possible (see also the Jackson Laboratory web site, http://www.jax.org/) and the ever-expanding collection of molecular tools. To enhance the utility of the mouse system, we initiated a program to generate a large database of expressed sequence tags (ESTs) that can provide rapid access to genes. Of particular significance was the possibility that cDNA libraries could be prepared from very early stages of development, a situation unrealized in human EST projects. We report here the development of a comprehensive database of ESTs for the mouse. The project, initiated in March 1996, has focused on 5' end sequences from directionally cloned, oligo-dT primed cDNA libraries. As of 23 October 1998, 352,040 sequences had been generated, annotated and deposited in dbEST, where they comprised 93% of the total ESTs available for mouse. EST data are versatile and have been applied to gene identification, comparative sequence analysis, comparative gene mapping and candidate disease gene identification, genome sequence annotation, microarray development and the development of gene-based map resources.

Animals↗
PubMed1999

Early developmental experiences of female sex workers: a comparative study.

OBJECTIVE: The aim of this paper is to explore the early family environment of a sample of female sex workers and compare the findings with a large community data set of similarly aged women. METHOD: Sex workers recruited by a snowball method were given a semi-structured interview, which included the Parental Bonding Instrument. These results were compared to those from the Otago Women's Child Sexual Abuse (OWCSA) study. RESULTS: The sex workers' families were of lower socioeconomic status and had experienced more parental separation than had the OWCSA families. The mothers of sex workers were more frequently the family's main wage earner. Sex workers described both parents as less caring than did the OWCSA women. They were significantly more likely than the OWCSA women to report childhood sexual abuse. The sex workers were more likely to have left home early, to have become pregnant before the age of 19 years and to not have completed tertiary study. CONCLUSIONS: The sex workers studied came from families with more interpersonal difficulties during childhood and adolescence than did a control community sample of similarly aged women. The relevance and generalisability of this conclusion to the wider sex worker population is difficult to determine, given the non-random selection of this sex worker sample.

Adolescent↗
PubMed1999

Selection of maternal human immunodeficiency virus type 1 variants in human placenta. European Network for In Utero Transmission of HIV-1.

To determine the mechanisms by which human immunodeficiency virus type 1 (HIV-1) crosses the placenta into the fetal blood, 12 matched samples of serial maternal blood, term placentas, and infant blood obtained from a cohort of pregnant women in Cameroon identified as predominantly infected by subtype A viruses were studied. HIV-1 env sequences were detected by polymerase chain reaction (PCR) in both chorionic villi and enriched trophoblastic cells of all 12 placentas but at variable rates of detection. Heteroduplex mobility assay analysis showed the presence of multiple HIV-1 env quasispecies in sequential maternal peripheral blood mononuclear cell samples, but only a small number of env variants were found in chorionic villi and enriched trophoblastic cells. These data indicate that HIV-1 env sequences are always present in term placentas of seropositive women, contrasting with the low frequency at which infection is diagnosed by PCR in neonates with tat, gag, and env primers. Maternal HIV-1 variants appear to undergo a strong negative selection by different cell populations within the placental villi.

Base Sequence↗
PubMed1999

Precision and method bias of two assays for oestradiol: consequences for decisions in assisted reproduction.

Oestradiol monitoring in assisted reproduction is empirical, with no proof of benefit. Precise oestradiol estimation will be an essential pre-requisite for high quality evaluation of possible differences between combined and ultrasound-only monitoring. Objectives of the present trial were independent method comparison and bias estimation of chemiluminescent immunoassay (CLIA) versus radioimmunoassay for oestradiol. In a prospective comparison, 505 consecutive samples were split and assayed concurrently. Precision (reproducibility), relative bias and logistics were analysed and compared to manufacturers' findings. Correlation between CLIA and radioimmunoassay was excellent. Positive bias with CLIA necessitated altering decision points for therapy. Precision (reproducibility) was superior with CLIA, making it an appropriate candidate method for future randomized trials of the effectiveness of combined oestradiol/ultrasound monitoring for assisted reproduction.

Decision Making↗
PubMed1999

Evaluating cardiovascular disease prevention programs in African American communities.

This article reports on an evaluation of community cardiovascular disease prevention projects. The evaluation protocol involved a monitoring system for documenting community activities. It showed improvements in cardiovascular disease prevention services, community actions, planned products, and new or modified community programs to prevent cardiovascular disease. Reports from focus group sessions provided analyses of participants' perceived behaviors and satisfaction with eight community-based cardiovascular disease prevention projects in African American communities. Modest improvements in blood pressure, blood cholesterol, dietary intake, and physical activity among a convenience sample of participants in the community were noted.

Adult↗
PubMed1999

Interclass transmission and phyletic host tracking in murine leukemia virus-related retroviruses.

Retroviruses are capable of infectious horizontal transmission between hosts, usually between individuals within a single species, although a number of probable zoonotic infections resulting from transmission between different species of placental mammals have also been reported. Despite these data, it remains unclear how often interspecies transmission events occur or whether their frequency is influenced by the evolutionary distance between host taxa. To address this problem we used PCR to amplify and characterize endogenous retroviruses related to the murine leukemia viruses. We show that members of this retroviral genus are harbored by considerably more organisms than previously thought and that phylogenetic analysis demonstrates that viruses isolated from a particular host class generally cluster together, suggesting that infectious virus horizontal transfer between vertebrate classes occurs only rarely. However, two recent instances of transmission of zoonotic infections between distantly related host organisms were identified. One, from mammals to birds, has led to a rapid adaptive radiation into other avian hosts. The other, between placental and marsupial mammals, involves viruses clustering with recently described porcine retroviruses, adding to concerns regarding the xenotransplantation of pig organs to humans.

Amino Acid Sequence↗
PubMed1999

Human transcription factor hTAF(II)150 (CIF150) is involved in transcriptional regulation of cell cycle progression.

Here we present evidence that CIF150 (hTAF(II)150), the human homolog of Drosophila TAF(II)150, plays an important and selective role in establishing gene expression patterns necessary for progression through the cell cycle. Gel filtration experiments demonstrate that CIF150 (hTAF(II)150) seems to be less tightly associated with human transcription factor IID than hTAF(II)130 is associated with hTAF(II)250. The transient functional knockout of CIF150 (hTAF(II)150) protein led to cell cycle arrest at the G(2)/M transition in mammalian cell lines. PCR display analysis with the RNA derived from CIF150-depleted cells indicated that CIF150 (hTAF(II)150) is required for the transcription of only a subset of RNA polymerase II genes. CIF150 (hTAF(II)150) directly stimulated cyclin B1 and cyclin A transcription in cotransfection assays and in vitro assays, suggesting that the expression of these genes is dependent on CIF150 (hTAF(II)150) function. We defined a CIF150 (hTAF(II)150) consensus binding site and demonstrated that a CIF150-responsive cis element is present in the cyclin B1 core promoter. These results suggest that one function of CIF150 (hTAF(II)150) is to select specific RNA polymerase II core promoter elements involved in cell cycle progression.

Cell Cycle↗
PubMed1999

Human angiotensin I-converting enzyme gene and endurance performance.

Human physical performance is strongly influenced by genetic factors. A variation in the structure of the human angiotensin I-converting enzyme (ACE) gene has been reported in which the insertion (I) variant is associated with lower ACE levels than the deletion (D) gene. We have previously reported that the I variant was associated with improved endurance performance in high-altitude mountaineers and British Army recruits. We now examine this genotype distribution in 91 British Olympic-standard runners (79 Caucasians). DNA was extracted from the buccal cells contained in 10 ml of saline mouthwash donated by the subjects, and the I and D variants of the ACE gene were identified by PCR amplification of the polymorphic region. There was an increasing frequency of the I allele with distance run [0.35, 0.53, and 0.62 for </=200 m (n = 20), 400-3,000 m (n = 37), and >/=5,000 m (n = 34), respectively; P = 0.009 for linear trend]. Among 404 Olympic-standard athletes from 19 other mixed sporting disciplines (in which endurance performance was not necessarily a key factor), the I allele did not differ significantly from that found in control subjects: 0.50 vs. 0.49 (P = 0.526). These results support a positive association of the I allele with elite endurance performance.

Alleles↗
PubMed1999

Classical Friedreich's ataxia and its genotype.

Fourteen patients with classical features of Friedreich's ataxia (FRDA) were examined. The clinical diagnosis of FRDA was afterwards confirmed in all patients by the appropriate DNA investigation which showed markedly increased amounts of GAA repeats on both alleles of the frataxin gene. None of our patients presented with atypical features such as late-onset FRDA, FRDA with retained deep tendon reflexes or with a very slow course. Five of them are not yet confined to a wheelchair. But for 1 patient who died at age 36 years and had the largest number of GAA repeats on both alleles, there was no significant correlation between number of repeats in the shortest allele, age at onset, age at wheelchair dependence, duration of the disease and main clinical signs. All patients but 3 had between 500 and 1,050 GAA repeats. The 3 patients with, respectively, 400, 450 and 500 repeats on the shortest allele had a clinical course comparable to the other patients. Even in the case of variations in the number of repeats in the same sibship, there were only modest differences between the siblings concerning age at onset of the disease, symptoms and signs and age at wheelchair dependence. There were no qualitative differences in the main clinical features and laboratory investigations in the full-blown phase of the disorder. Molecular biology has become a major element in the diagnosis of FRDA. DNA testing for FRDA should be applied to every case of idiopathic autosomal recessive or sporadic ataxia. However, the clinical features of FRDA remain fully characteristic in many patients and keep their diagnostic value.

Adolescent↗
PubMed1999

Longitudinal aneurysm shrinkage following endovascular aortic aneurysm repair: a source of intermediate and late complications.

PURPOSE: To report the incidence of delayed complications following endovascular abdominal aortic aneurysm (AAA) repair and the relationship of these sequelae to morphological changes in the sac and endograft. METHODS: Twenty-six AAA patients treated with Vanguard endografts had completed > or = 1-year follow-up. Postoperative angiograms and spiral computed tomographic (CT) scans with 3-dimensional reconstruction were compared to the 1-year images to determine morphological changes in the aneurysm sac and the endograft. These changes were then related to complications occurring between 1 and 12 months postoperatively in the study group. RESULTS: Comparison of angiograms uncovered endograft buckling in 18 (69%) patients and acutely angled or kinked endografts in 10 (38%). Measurements from the CT scans found that undistorted endografts had a mean change in sac length of +6.6 mm. Mean sac length change in buckled endografts was -3.1 mm, while kinked endografts displayed a mean change of -6.2 mm (p < 0.002, Student's t-test). Five (19%) patients, all with distorted endografts, demonstrated late (1 to 12 months) complications (4 endoleaks and 1 graft limb thrombosis) owing to component separation, distal stent migration, and acute angulation. No movement in the proximal stent was observed. Elongation of the endograft (flow line measurement) was observed in one tube graft only. CONCLUSIONS: In this study, longitudinal shrinkage of the sac following endovascular aortic aneurysm repair led to buckling or kinking of the endograft within 1 year in 69% of patients. This appears to be an important source of delayed complications.

Aged↗
PubMed1999

Magnetic resonance imaging compatibility testing of intracranial pressure probes. Technical note.

There is increasing recognition that magnetic resonance (MR) imaging and spectroscopy may provide important information in the assessment of patients with acute brain injury. However, optimum care of the acutely head injured patient requires monitoring of intracranial pressure (ICP). Although many monitoring modalities have been integrated into commercially available MR-compatible systems, there have been no reports of commonly used intraparenchymal ICP sensors in an MR environment. The authors describe the use of an ICP micromanometer probe in an MR environment, with a fiberoptic connection that interfaces the probe with a commercially available MR-compatible monitoring system. Phantom studies were performed to demonstrate the safety and compatibility of the modified MR system at 0.5 tesla. The safety of the device was assessed in relation to its interaction with the static, gradient, and radiofrequency fields used in MR imaging. The MR compatibility was documented by demonstrating that its performance was unaffected by the operation of imaging sequences and by showing that there was no degradation of the diagnostic quality of imaging data obtained during ICP monitoring.

Equipment Design↗
PubMed1999

Divergent effects of paracetamol on reactive oxygen intermediate and reactive nitrogen intermediate production by U937 cells.

We investigated the effects of paracetamol on reactive oxygen intermediate and reactive nitrogen intermediate production by U937 cells. Cells which had been treated with paracetamol (0.01 microM - 10 microM) exhibited a significant (p<0.001) increase in hydrogen peroxide production and a significant (p<0.001) increase in phorbol 12-myristate 13-acetate induced superoxide production. Conversely, paracetamol (0.01 microM - 10 microM) caused a significant (p<0.001) decrease in the amount of nitrite secreted into the culture medium. Our results indicate divergent effects of paracetamol on ROI and RNI production.

Acetaminophen↗
PubMed1999

The influence of clinical variables on hospital costs after orthotopic liver transplantation.

BACKGROUND: The burgeoning influence of managed care in transplantation, coupled with a shrinking health-care dollar, has placed most transplant programs under intense pressure to cut costs. We undertook a retrospective cost-identification analysis to determine what clinical variables influenced financial outcomes after orthotopic cadaver liver transplants (OLTx). METHODS: Fifty patients receiving 53 transplants between April 1995 and November 1996 were reviewed. Clinical data were obtained from our institution's transplant database, and total costs (not charges) for the transplant admission and the 6 months after transplant were obtained with use of an activity-based cost accounting system (HBOC Trendstar, Atlanta, Ga). RESULTS: The average total cost of second transplants (n = 5) was $97,262 greater than for first transplants (n = 48, P < .05). Patients transplanted initially as United Network for Organ Sharing (UNOS) status 2 (n = 20) incurred average costs that were $51,762 higher than for patients transplanted as UNOS status 3 (n = 28, P = .008). Patients with a major bacterial or fungal infection (n = 28) incurred average costs $46,282 higher than recipients who were infection free (n = 22, P = .02). Multivariate analysis demonstrated that only length of stay, retransplantation, and postoperative dialysis were significantly and independently correlated with costs (r2 = .605). When the model was repeated with preoperative variables alone, only UNOS status was significantly correlated with 6-month total costs (P = .006, r2 = .16). CONCLUSIONS: Length of stay is the most important determinant of costs after OLTx. Rational strategies to design cost-effective protocols after OLTx will require further studies to truly define the cost of various morbidities and outcomes after OLTx.

Adult↗