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Biomedical subjects

C Smith

Publications and source records attributed to C Smith.

At least 415 records · Page 23Linked to original sources

Restriction fragment length polymorphism in amplification products of the bovine butyrophilin gene: assignment of bovine butyrophilin to bovine chromosome 23.

A polymorphism was identified in the bovine butyrophilin (BTN) gene by digesting polymerase chain reaction products with the restriction enzyme HaeIII. This polymorphism was segregating in a Holstein-Friesian sire selected as part of an ongoing study directed towards the identification of quantitative trait loci affecting milk composition. Screening of a half-sib family established for the heterozygous sire allowed the localization of BTN to bovine chromosome 23 (BTA23).

Animals↗

Once-daily aminoglycoside therapy: potential ototoxicity.

Current data indicate that once-daily aminoglycoside therapy is as efficacious as traditional multiple daily dosing and equally or less toxic. Our experience with once-daily gentamicin, 6 mg/kg of body weight led to a 10% (3 of 33 patients) occurrence of documented ototoxicity after prolonged aminoglycoside exposure.

Aged↗

Monitoring Babesia bovis infections in cattle by using PCR-based tests.

The sensitivity and specificity of PCR tests based on the small-subunit rRNA gene sequence of Babesia bovis were compared in a blind study of experimentally infected cattle with the corresponding parameters of the complement fixation (CF) test currently used in the United States to screen for bovine babesiosis. Cattle were experimentally infected with a single inoculum of a cloned laboratory strain of B. bovis. Blood samples were collected and tested over a period covering from the day of infection to 10 months postinfection. The level of parasitemia (percent infected erythrocytes) present in each sample was estimated from test results and was plotted as a function of time postinfection. These data are the first describing the course of infection by methods capable of detecting parasitemias in the range of 10(-7)%, which frequently occur in the carrier state. Parasitemias in the samples tested strongly influenced the sensitivity and negative predictive value of the PCR-based tests which varied with time postinfection. The average sensitivities of the three PCR-based tests for B. bovis ranged from 58 to 70% for a single determination, while the sensitivity of the CF test was only 6%. Both PCR-based and CF tests for B. bovis had high specificity values ranging from 96 to 100%.

Animals↗

Mucosal factors inducing neutrophil movement in ulcerative colitis: the role of interleukin 8 and leukotriene B4.

BACKGROUND: The movement of neutrophils into the colonic mucosa in ulcerative colitis is induced by chemokines including interleukin 8 (IL8) and leukotriene B4 (LTB4). AIMS: To compare the ability of mucosa from ulcerative colitis patients and controls to stimulate neutrophil movement, to define the contribution of LTB4 to this, and to define the relative biological importance of LTB4 and IL8. PATIENTS: Resected mucosa was obtained from seven control patients and 10 patients with ulcerative colitis. METHODS: Mucosal homogenate supernatants were used to stimulate isolated neutrophils and the effect assessed by the neutrophil shape change response. Responses were inhibited with either the LTB4 receptor antagonist SC41930- or neutralising anti-IL8 antibody. LTB4 was extracted and assayed by RIA. RESULTS: Homogenate supernatants from inflamed mucosa were more bioactive (median 1.2 mg/ml-1 induced 50% response) than those from uninflamed mucosa (4.25 mg/ml-1 induced 50% response; difference 2.8 mg/ml-1 (96.5% CI 0.5 to 6.1, p < 0.05). Maximal inhibition by SC41930 of the response was significantly greater in inflamed mucosa (54% median) than in uninflamed mucosa (34%). This inhibition correlated with the level of immunoreactive LTB4 (r = 0.78). Anti-IL8 reduced bioactivity of homogenate supernatants from inflamed mucosa (at 1:10 dilution) by 11.4% (IQR 1.2 to 51.8, p = 0.021) whereas SC41930 reduced it by 54.8% (35.6 to 77.5, p = 0.008). CONCLUSIONS: Inflamed colonic mucosa releases more neutrophil movement inducing bioactivity than uninflamed mucosa, and has greater LTB4 dependent activity. It yields both IL8 and LTB4 dependent activity but greater LTB4 dependent activity.

Adult↗

The active site of myosin.

The significance of myosin has been expanded recently with the realization that it is found in every eukaryotic cell, where it has a role in cytokinesis, cell division, and vesicle transport. Advances in molecular genetics and expression systems related to myosin and actin have helped to reveal the extent of the myosin superfamily. New motility assays and techniques have provided information about the residues involved in ATP hydrolysis and the conformational change induced by nucleotide binding. The results of these techniques revealing structural and functional information combined with previous studies of the active site of myosin should provide future direction for studying this exciting and rapidly moving area of biochemistry.

Amino Acid Sequence↗

24,25 Dihydroxyvitamin D supplementation corrects hyperparathyroidism and improves skeletal abnormalities in X-linked hypophosphatemic rickets--a clinical research center study.

Therapy for X-linked hypophosphatemia (XLH) only partially corrects skeletal lesions and is often complicated by hyperparathyroidism. 24,25(OH)2 D3 improves skeletal lesions in a murine model of XLH and suppresses PTH secretion in animals. Therefore, we undertook a placebo-controlled trial of 24,25(OH)2 D3 supplementation to standard treatment in patients with XLH to improve bone disease and reduce hyperparathyroid complications. Fifteen subjects with XLH receiving standard treatment [1,25(OH)2 D3 or dihydrotachysterol plus phosphate] were evaluated, supplemented with placebo, and reevaluated one yr later. 24,25(OH)2 D3 supplementation was then begun and studies repeated after another year. Each patient underwent a detailed evaluation of calcium homeostasis over a 24-h period. Rachitic abnormalities were assessed radiographically in children. Adults underwent bone biopsies. 24,25(OH)2 D3 normalized PTH values in nine subjects (peak PTH was 46.5 +/- 6.6 pmol/L at entry, 42.3 +/- 5.9 pmol/L after placebo, and 23.3 +/- 5.4 pmol/L after 24,25(OH)2 D3). Nephrogenous cAMP decreased at night, coincident with the decrease in PTH, and serum phosphorus was slightly greater with 24,25(OH)2 D3. Radiographic features of rickets improved during 24,25(OH)2 D3 supplementation in children, and osteoid surface decreased in adults. 24,25(OH)2 D3 is a useful adjunct to standard therapy in XLH by effecting correction of hyperparathyroidism and improvement of rickets and osteomalacia.

24,25-Dihydroxyvitamin D 3↗

Magnetic compass cues and visual pattern learning in honeybees

We show that honeybees can learn to distinguish between two 360 &deg; panoramic patterns that are identical except for their compass orientation; in this case, the difference was a 90 &deg; rotation about the vertical axis. To solve this task, bees must learn the patterns with respect to a directional framework. The most powerful cue to direction comes from the sky, but discrimination between patterns is possible in the absence of celestial information. Under some conditions, when other potential directional cues have been disrupted, we show that bees can use a magnetic direction to discriminate between the patterns.

Journal Article↗

Immunohistochemical staining of fixed tissue using antigen retrieval and a thermal cycler.

The use of monoclonal antibodies to identify antigens in perfused fixed tissue is currently very challenging. Recently, many antigen retrieval methods have been described that require heating the tissue on slides using a microwave oven. Here, we describe a protocol for antigen retrieval that uses a commercially available solution called Citra and a DNA thermal cycler to heat the tissue sections. This method (i) allows for precise control of the temperature and time (unlike the microwave oven), (ii) uses very small quantities of the antigen retrieval solution, (iii) stains either free-floating sections or sections mounted on slides and (iv) achieves uniform staining throughout the tissue. In the paraformaldehyde-perfused fixed rat cerebellum, the monoclonal antibody glial fibrillary acidic protein conveys the clarity of the Bergmann and stellate glia in the strata. Scanning confocal images through the center of the tissue demonstrates the depth of antibody penetration achieved using this method. Finally, using a monoclonal antibody against the simian virus 40 (SV40) T antigen allowed positive, unequivocal identification of a grafted cell line, immortalized using SV40 T protein, thus demonstrating the true value of this method in an experimental paradigm.

Aldehydes↗

DNA sequencing with [alpha-33P]-labeled ddNTP terminators: a new approach to DNA sequencing with Thermo Sequenase DNA polymerase.

A new approach to DNA sequencing is described. The method is based on the use of [alpha-33P]-labeled dideoxyribonucleoside triphosphate terminators and Thermo Sequenase DNA polymerase in cycle sequencing. Thermo Sequenase DNA polymerase incorporates ddNTPs as efficiently as dNTPs, allowing the use of low concentrations of these nucleotides in DNA sequencing. Because only the properly terminated chains are labeled and visualized on autoradiography of the sequencing gels, the sequence results are free of background. The intensity of DNA bands generated are remarkably uniform, which makes reading of DNA sequences easy. By staggered loading of the sequencing gel (at 2-3 hour intervals), it is possible to sequence DNA at least 450 to 500 nucleotides. Exposure time for autoradiography with [alpha-33P] labels is much shorter than with [35S] and does not substantially compromise autoradiographic resolution. Data can be obtained after only 12 hours of exposure of an X-ray film. Moreover, cycle sequencing requires very small amounts of single- or double-stranded template. Consequently, it is even possible to generate sequence data from a single bacterial colony. The details of the protocol are presented in a stepwise manner, and some important parameters to be considered for sequencing with this method are discussed.

Codon, Terminator↗

CT appearance of pulmonary vasculitis in children.

OBJECTIVE: The aim of this study was to determine whether a CT pattern that may represent early or subtle changes of pulmonary vasculitis in children exists. MATERIALS AND METHODS: High-resolution CT scans of the chest for 107 children were retrospectively reviewed by two radiologists who were unaware of the original study findings. Chest CT scans (conventional) for another 54 children who had symptoms or a diagnosis of vasculitis also were reviewed. RESULTS: We identified hazy or fluffy centrilobular, perivascular densities in 10 children, two of whom had small airways disease and eight of whom had vasculitis (Wegener's granulomatosis [n = 5], systemic lupus erythematosus [n = 1], scleroderma-polymyositis overlap syndrome [n = 1], and Churg-Strauss syndrome [n = 1]). The latter eight children underwent 35 scans, 17 of which were positive for these perivascular densities. All positive scans were associated with active disease of new onset (5/17) or with clinical exacerbation of preexisting systemic disease (12/17). The positive scans also were associated with an elevated erythrocyte sedimentation rate (13/17) and biopsy evidence of vasculitis from a variety of sites, including the lungs (n = 1), kidneys (n = 7), oropharynx (n = 5), skin (n = 9), lymph nodes (n = 1), and myocardium (n = 2). The single lung biopsy showed an angiocentric inflammatory-hemorrhagic process. Of the five patients who had positive scans, underwent therapy, and then had repeat studies, four patients had scans revert to normal in association with inactive disease. The remaining patient whose scan did not normalize failed to respond to treatment. CONCLUSION: The fluffy centrilobular pattern likely represents subtle changes of pulmonary vasculitis. In the appropriate clinical setting, such a finding may obviate the need for a lung biopsy.

Adolescent↗

LY290181, an inhibitor of diabetes-induced vascular dysfunction, blocks protein kinase C-stimulated transcriptional activation through inhibition of transcription factor binding to a phorbol response element.

Previous studies have shown that high glucose levels and diabetes induce an elevation in protein kinase C (PKC) activity in vascular cells and tissues susceptible to diabetic complications. In addition, PKC activation has been shown to modulate vascular cell growth, permeability, and gene expression, processes thought to be involved in the development of vascular complications. Using two in vivo model systems, we have identified a novel inhibitor of diabetic vascular dysfunction, LY290181. LY290181 prevented glucose-induced increases in blood flow and permeability in rat granulation tissue and corresponding vascular changes in the retina, sciatic nerve, and aorta of diabetic rats. Tested for its ability to inhibit PKC-regulated processes, LY290181 inhibited phorbol ester-stimulated plasminogen activator activity in a dose-dependent manner in bovine retinal endothelial cells and in human dermal fibroblasts. In addition, LY290181 inhibited phorbol ester-stimulated activation of the porcine urokinase plasminogen activator (uPA) promoter (-4600/+398) linked to the chloramphenicol acetyltransferase (CAT) reporter gene (p4660CAT). More detailed analysis of the uPA promoter revealed that LY290181 inhibited phorbol ester-stimulated activation of the uPA phorbol response element (-2458/-2349) located upstream of the thymidine kinase promoter (puPATKCAT). LY290181 appears to inhibit uPA promoter activation by blocking phorbol ester-stimulated binding of nuclear proteins to the uPA PEA3/12-0-tetradecanoylphorbol 13-acetate responsive element (TRE). These results suggest that LY290181 may inhibit diabetes-induced vascular dysfunction by inhibiting transcription factor binding to specific PKC-regulated genes involved in vascular function.

Animals↗

IS outlook '96: predictions & predilections. Roundtable discussion.

Musings from some of the leading national and international HIT organizations make it clear that the need for a computer-based patient record is approaching the critical point. Half of our respondents identified the CPR as the single most important technology in 1996. One of our participants goes so far as to say that the era prior to the electronic medical record will one day be remembered as the "paper age." Progress in the development of standards--crucial to the CPR--could be dramatic this year, say experts from two of the major standards organizations. For a look at these issues and others, including key government policies to watch this year, read on.

Computer Communication Networks↗

High-efficiency retroviral vector mediated gene transfer into human peripheral blood CD4+ T lymphocytes.

Genetic modification of peripheral blood T lymphocytes has been proposed as a therapeutic strategy for treating congenital disorders, cancer and viral diseases. Central to all T lymphocyte-based gene therapy strategies is the ability to efficiently and stably deliver genes into primary T lymphocytes. In this study, we sought to increase the gene transfer efficiency in CD4+ peripheral blood T lymphocytes using procedures which could be utilized in clinical applications. In order to quantity the gene transfer efficiency in primary CD4+ T cells, a high-titer retroviral vector which efficiently expresses a truncated version of the human low-affinity nerve growth factor receptor (delta LNGFR) was constructed. Transduced cells were then accurately enumerated with immunofluorescence staining and fluorescence activated cell sorting (FACS) analysis and rapidly isolated at high purity for further analysis. Using this system, a supernatant-based gene transfer procedure was developed which routinely yields gene transfer efficiencies of 25-40% into a wide repertoire of both freshly obtained and cryopreserved peripheral blood CD4+ T lymphocytes.

3T3 Cells↗

Parameterization studies for the SAM and HMMER methods of hidden Markov model generation.

Multiple sequence alignment of distantly related viral proteins remains a challenge to all currently available alignment methods. The hidden Markov model approach offers a new, flexible method for the generation of multiple sequence alignments. The results of studies attempting to infer appropriate parameter constraints for the generation of de novo HMMs for globin, kinase, aspartic acid protease, and ribonuclease H sequences by both the SAM and HMMER methods are described.

Aspartic Acid Endopeptidases↗