Biomedical subjects

Michael Weir

Publications and source records attributed to Michael Weir.

12 recordsLinked to original sources

PubMed2006

Arsenic removal by electrocoagulation using combined Al-Fe electrode system and characterization of products.

Combination of electrodes, such as aluminum and iron in a single electrochemical cell provide an alternative method for removal of arsenic from water by electrocoagulation. The removal process has been studied with a wide range of arsenic concentration (1-1000 ppm) at different pH (4-10). Analysis of the electrochemically generated by-products by XRD, XPS, SEM/EDAX, FT-IR, and Mössbauer Spectroscopy revealed the expected crystalline iron oxides (magnetite (Fe3O4), lepidocrocite (FeO(OH)), iron oxide (FeO)) and aluminum oxides (bayerite (Al(OH)3), diaspore (AlO(OH)), mansfieldite (AlAsO(4).2(H2O)), as well as some interaction between the two phases. The amorphous or very fine particular phase was also found in the floc. The substitution of Fe3+ ions by Al3+ ions in the solid surface has been observed, indicating an alternative removal mechanism of arsenic in these metal hydroxides and oxyhydroxides by providing larger surface area for arsenic adsorption via retarding the crystalline formation of iron oxides.

Aluminum↗

PubMed2006

Challenging the spliceosome machine.

BACKGROUND: Using cDNA copies of transcripts and corresponding genomic sequences from the Berkeley Drosophila Genome Project, a set of 24,753 donor and acceptor splice sites were computed with a scanning algorithm that tested for single nucleotide insertion, deletion and substitution polymorphisms. Using this dataset, we developed a progressive partitioning approach to examining the effects of challenging the spliceosome system. RESULTS: Our analysis shows that information content increases near splice sites flanking progressively longer introns and exons, suggesting that longer splice elements require stronger binding of spliceosome components. Information also increases at splice sites near very short introns and exons, suggesting that short splice elements have crowding problems. We observe that the information found at individual splice sites depends upon a balance of splice element lengths in the vicinity, including both flanking and non-adjacent introns and exons. CONCLUSION: These results suggest an interdependence of multiple splicing events along the pre-mRNA, which may have implications for how the macromolecular spliceosome machine processes sets of neighboring splice sites.

Animals↗

PubMed2005

Arsenic removal via electrocoagulation from heavy metal contaminated groundwater in La Comarca Lagunera México.

Arsenic contamination is an enormous worldwide problem. A large number of people dwelling in Comarca Lagunera, situated in the central part of northern México, use well water with arsenic in excess of the water standard regulated by the Secretary of Environment and Natural Resources of México (SEMARNAT), to be suitable for human health. Individuals with lifetime exposure to arsenic develop the classic symptoms of arsenic poisoning. Among several options available for removal of arsenic from well water, electrocoagulation (EC) is a very promising electrochemical treatment technique that does not require the addition of chemicals or regeneration. First, this study will provide an introduction to the fundamental concepts of the EC method. In this study, powder X-ray diffraction, scanning electron microscopy, transmission Mössbauer spectroscopy and Fourier transform infrared spectroscopy were used to characterize the solid products formed at iron electrodes during the EC process. The results suggest that magnetite particles and amorphous iron oxyhydroxides present in the EC products remove arsenic(III) and arsenic(V) with an efficiency of more than 99% from groundwater in a field pilot scale study.

Arsenic↗

PubMed2005

Missed breast cancer: the legal factors.

Any reading of the relevant legal authorities confirms the special difficulties involved in the diagnosis of breast cancer. In many cases a delayed diagnosis of breast cancer is made at a time when a patient's position has become terminal. It is an easy task for lawyers and expert witnesses to determine in hindsight what should have been done at some point in the past. This article describes how the courts have dealt with this issue and comments on appropriate procedures and approaches to both protect the interests of the patient and confine liability for the medical practitioner.

Australia↗

PubMed2005

Index of suspicion.

Explore the source record for details and available documents.

Chelating Agents↗

PubMed2004

Bone formation in polymeric scaffolds evaluated by proton magnetic resonance microscopy and X-ray microtomography.

Magnetic resonance microscopy (MRM) and X-ray microtomography (XMT) were used to investigate de novo bone formation in porous poly(ethyl methacrylate) (PEMA) scaffolds, prepared by a novel co-extrusion process. PEMA scaffolds were seeded with primary chick calvarial osteoblasts and cultured under static conditions for up to 8 weeks. Bone formation within porous PEMA scaffolds was confirmed by the application of histologic stains to intact PEMA disks. Disks were treated with Alizarin red to visualize calcium deposits and with Sirius red to visualize regions of collagen deposition. DNA analysis confirmed that cells reached confluence on the scaffolds after 7 weeks in static culture. The formation of bone in PEMA scaffolds was investigated with water proton MRM. Quantitative MRM maps of the magnetization transfer ratio (MTR) yielded maps of protein deposition, and magnetic resonance (MR) relaxation times (T1 and T2) yielded maps of mineral deposition. The location of newly formed bone and local mineral concentrations were confirmed by XMT. By comparing MRM and XMT data from selected regions-of-interest in one sample, the inverse relationship between the MR relaxation times and mineral concentration was validated, and calibration curves for estimating the mineral content of cell-seeded PEMA scaffolds from quantitative MRM images were developed.

Animals↗

PubMed2004

Ordered partitioning reveals extended splice-site consensus information.

Using recently available cDNA and genomic data (Berkeley Drosophila Genome Project; http://www.fruitfly.org), we computed a large sample of 10,057 Drosophila splice sites. An information-theoretic analysis of the nucleotide sequences adjacent to these splice sites showed a strong correlation between the sizes of introns and exons and the levels of information, which is a measure of sequence conservation. The strong correlation permitted us to determine extensive consensus sequences at the donor and acceptor sites of longer introns. These sequences were further refined and extended by examining the information in regions around splice sites that only partially matched the consensus. The correlation between length and information provided the basis for determining alternative consensus arrangements associated with shorter introns, as well as general base-composition preferences that likely promote spliceosome function. We also observed a correlation between information near splice sites and the lengths of nonadjacent introns, indicating that there are long-range effects spanning multiple introns. The ordered partitioning approach used in this analysis may become increasingly useful as large genomic data sets become available.

Animals↗

PubMed2004

Relational databases: a transparent framework for encouraging biology students to think informatically.

We discuss how relational databases constitute an ideal framework for representing and analyzing large-scale genomic data sets in biology. As a case study, we describe a Drosophila splice-site database that we recently developed at Wesleyan University for use in research and teaching. The database stores data about splice sites computed by a custom algorithm using Drosophila cDNA transcripts and genomic DNA and supports a set of procedures for analyzing splice-site sequence space. A generic Web interface permits the execution of the procedures with a variety of parameter settings and also supports custom structured query language queries. Moreover, new analytical procedures can be added by updating special metatables in the database without altering the Web interface. The database provides a powerful setting for students to develop informatic thinking skills.

Algorithms↗

PubMed2003

Obligation to advise of options for treatment--medical doctors and complementary and alternative medicine practitioners.

An important aspect of health professional's duty of care is to advise patients of the available options of treatment so that the patient can choose the form of treatment that suits her or his requirements. As CAM becomes more evidence-based and accepted, medical doctors need to consider the extent to which they should provide patients with information about those types of treatments. If a CAM treatment option is evidence-based, there is a strong argument that medical doctors should advise of this option for treatment to satisfy their duty. CAM practitioners should also provide details of options for treatment within their own modality but are not obliged to advise of medical options.

Australia↗

PubMed2002

A conserved F-box gene with unusual transcript localization.

Drosophila partner of paired ( ppa), which encodes an F-box protein that targets the Pax transcription factor Paired (Prd) for degradation, has the striking property that its mRNA is expressed in a striped pattern with a characteristic registration relative to the striped expression of prd in early embryos. Localized expression of F-box genes was not expected because F-box proteins generally have multiple substrates. We hypothesize that the patterned mRNA expression of Drosophila and zebrafish ppa homologs may reflect constraints resulting from the localized expression of their degradation substrates. To begin to test this idea, we wished to determine whether patterned mRNA expression is commonly observed among F-box genes, or whether it might be peculiar to ppa and its homologs, or even specific to Drosophila. We examined embryonic expression of all predicted F-box genes in Drosophila and found that mRNAs of 21 out of 23 predicted F-box genes are expressed uniformly in early Drosophila embryos, whereas ppa and CG4911 mRNAs are patterned, CG4911 being expressed at the positions of gastrulation folds. We also identified and tested expression of ppa in zebrafish, which has two highly conserved homologs, ppaA and ppaB, and found that both are expressed during embryogenesis and have enriched mRNA expression in regions including the neural tube, the head, and the fin buds. Despite being unusual in having localized transcripts, we found that the Drosophila and zebrafish homologs interact with the expected Drosophila components of the cellular degradation machinery - Skp1 (SkpA) and Rbx1 (Roc1a) - suggesting that the Ppa proteins are indeed functional F-box proteins. We conclude that patterning of ppa mRNA could reflect a constraint on ppa function that is not common among F-box genes. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00427-002-0222-7.

Amino Acid Sequence↗

PubMed2002

Urinary tract infection as a possible marker for teenage sex.

BACKGROUND: Pediatric urinary tract infections (UTIs) are markers for genitourinary reflux or obstruction. Adult UTIs are treated by telephone triage without microbiologic study. The contrast between pediatric and adult UTIs prompted our retrospective review of adolescent UTIs. METHODS: Ninety-six adolescent girls without chronic illness, urogenital abnormalities, pregnancy, enuresis, or constipation had urine cultures with 100,000 colonies/mm3. RESULTS: The 32 patients who were initially sexually active continued sexual activity (75%), became pregnant (25%), and had subsequent sexually transmitted diseases (STDs) (13%). There were no pregnancies, STDs, or subsequent UTIs in 9 patients who were not initially sexually active. The 55 patients with no documentation of sexual activity were comparable to those who were initially sexually active: 66% had evidence of sexual activity; 20% had subsequent pregnancy; 14% had subsequent STDs; and 42% had UTI recurrence. CONCLUSION: Adolescents with UTIs have a significant frequency of sexual activity. Information about responsible sexual activity and access to care is important to adolescents, particularly those with UTIs.

Adolescent↗

PubMedDate not supplied

Vocal cord dysfunction mimics asthma and may respond to heliox.

Vocal cord dysfunction (VCD), an under appreciated cause of wheezing, may be mistaken for or coexist with asthma. The vocal cords involuntarily adduct during inspiration, leading to inspiratory or biphasic wheezing. Asthma therapy offers no benefit and may result in injury. Proof of diagnosis requires endoscopy during an episode. Definitive therapy involves voice training by a speech pathologist, but heliox (20% to 40% oxygen in helium) has been used to reduce symptoms, resulting in dramatic improvement in wheezing and less anxiety. A retrospective review of recent experience with heliox treatment for patients with VCD was conducted, using a search of computerized inpatient and outpatient physician dictation reporting at Scott & White Memorial Hospital and Clinic. Five patients age 10 to 15 years were treated with a favorable response in four. There were no complications of therapy. A high index of suspicion can lead to the diagnosis of VCD, avoiding expensive, inappropriate, and harmful therapy. A trial of heliox inhalation for patients with symptomatic VCD may prove beneficial, analogous to the "reliever" role of beta agonists for asthma. Home or school use of heliox may reduce acute care visits, while voice training ("controller" therapy) is instituted.

Adolescent↗