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Biomedical subjects

C Barron

Publications and source records attributed to C Barron.

10 recordsLinked to original sources
PubMed1992

Transcription of the gene for the merozoite surface antigen MSA2 of the human malaria parasite Plasmodium falciparum during the asexual cycle.

The transcription of the Plasmodium falciparum gene for the MSA2 antigen has been studied throughout the parasite's asexual growth cycle. For this purpose poly(A)+ RNA from different times of the cycle was tested for the presence of the mRNA encoding MSA2 by in vitro translation and subsequent analysis of the translation products by immunoprecipitation with an antibody against MSA2. The results revealed that this mRNA is present in trophozoites, reaches the highest concentration during the transition from the trophozoite into the schizont stage, and persists until the cycle end. Minute amounts of this mRNA were also detected in rings. In addition, the data confirmed that the primary translation product is not proteolytically processed at any time of the cycle.

Animals↗
PubMed1992

An evaluation of empirically fitting a posterior toric hydrogel contact lens.

The performance of toric hydrogel contact lenses fit without the use of diagnostic trial lenses was evaluated. Fifty-four patients (107 eyes) were empirically fit with a back surface toric lens (DuraSoft 3 Optifit Contact Lens), with the contact lens prescription based solely on keratometry and refractive findings. An assessment of lens performance was based on measures of lens movement and centration, visual acuity, lens rotation, rotational stability and patient acceptance of vision. Final mean lens rotation was found to be 1.43 degrees nasal (standard deviation 5.89 degrees), with 51 percent of the eyes exhibiting no lens rotation. Seventy-five percent of the eyes achieved acuity equal to that of their best corrected spectacle acuity, and 95 percent of the eyes achieved acuity equal to or within one line of their optimal spectacle corrected acuity. These results compare favorably to previously reported success rates of fitting toric hydrogel lenses using both empirical and diagnostic fitting procedures.

Astigmatism↗
PubMed1991

Bioptic telescopic spectacles for motor vehicle driving.

Attaining independent daily living skills is the primary functional goal of low vision rehabilitation. One of the most important of these skills is the ability of the low vision patient to achieve independent travel. In many geographical areas, automobile driving is the only available means of transportation. The utilization of a bioptic telescopic spectacle (BTS) provides a mechanism for some visually impaired individuals to qualify for a driver's license. However, the use of bioptic telescopic spectacles for driving is an extremely complex and controversial issue. An overview of the current status of the driving laws in various states, the accident rates of bioptic telescopic drivers, and various alternative proposals for motor vehicle licensure for the visually handicapped will be discussed.

Automobile Driver Examination↗
PubMed1990

Going the distance: rural health care in Texas.

Many doctors and hospitals are being squeezed out of rural and small-town Texas, and some of the population is beginning to suffer a lack of medical care comparable to that of underdeveloped countries. These articles consider the problem and present some options for improving health care delivery to rural Texans.

Delivery of Health Care↗
PubMed1989

Minute amounts of RNA are synthesized from several regions of the bacteriophage Mu DNA during the lysogenic state.

The transcription of phage Mu DNA during the lysogenic state has been quantitatively analysed. For this purpose pulse-labelled RNA from two lysogens and from their nonlysogenic parental strains were hybridized to non-overlapping Mu DNA restriction fragments covering the whole phage genome. The data revealed that all regions of the prophage are transcribed at low rates and that phage promoters are involved in this transcription. For this study an improved assay for quantitative filter hybridization was employed. The high sensitivity and reproducibility that can be obtained with the assay make it suitable for the quantitative analysis of minute amounts of mRNA.

Bacteriophage mu↗
PubMed1989

An assay for quantitative nucleic acid hybridization on membrane filters.

A quantitative nucleic acid hybridization assay based on a 6-mm-diameter nitrocellulose membrane filter and only 20 microliters of hybridization mixture per determination is described. As a consequence of the small ratio of hybridization volume to membrane surface, the hybridization rates reached in this system are higher than those obtained at volume to surface ratios of conventional protocols, allowing even RNA at very low concentrations to complete hybridization. This advantage, together with the high reproducibility and hybrid stability obtained with the assay, increases the ability of the filter hybridization technique to analyze quantitatively minute amounts of RNA.

Bacteriophages↗
PubMed1989

Pseudomonas aeruginosa outer membrane lipoprotein I gene: molecular cloning, sequence, and expression in Escherichia coli.

Lipoprotein I (OprI) is one of the major proteins of the outer membrane of Pseudomonas aeruginosa. Like porin protein F (OprF), it is a vaccine candidate because it antigenically cross-reacts with all serotype strains of the International Antigenic Typing Scheme. Since lipoprotein I was expressed in Escherichia coli under the control of its own promoter, we were able to isolate the gene by screening a lambda EMBL3 phage library with a mouse monoclonal antibody directed against lipoprotein I. The monocistronic OprI mRNA encodes a precursor protein of 83 amino acid residues including a signal peptide of 19 residues. The mature protein has a molecular weight of 6,950, not including bound glycerol and lipid. Although the amino acid sequences of protein I of P. aeruginosa and Braun's lipoprotein of E. coli differ considerably (only 30.1% identical amino acid residues), peptidoglycan in E. coli, are identical. Using lipoprotein I expressed in E. coli, it can now be tested whether this protein alone, without P. aeruginosa lipopolysaccharide contaminations, has a protective effect against P. aeruginosa infections.

Amino Acid Sequence↗
PubMed1988

Transcriptional mapping of the bacteriophage Mu DNA.

The transcription of temperate phage Mu throughout lytic development was analysed quantitatively by hybridization of pulse-labelled RNA to full-length Mu DNA and to plasmids that define Mu DNA segments covering the whole phage genome. The transcription rate (i.e. binding data corrected for the incorporation rate of the radioactive precursor, for the size of the DNA template, and for the number of phage genomes present in the bacterium at the time of analysis) revealed three defined phases of Mu transcription: early (0 to 9 min), intermediate (between 9 and the interval 14 to 17 min) and late (from the interval 14 to 17 min onward). The analysis also revealed that the region comprising the genes involved in phage morphogenesis was organized into two independent 'late' transcription units.

Bacteriophage mu↗
PubMed1978

[Adrenal function in topic corticotherapy].

It has been shown that corticosteroids for dermatological use produce an inhibition of the adrenal function, and it is considered that in our milieu these products are used without any precise indication. In this study, 29 ambulatory children from 3 to 15 years of age were selected, who were suffering from dermatoses with different degrees of extension, on whom urinary 17-ketosteroids, 17-ketogenicsteroids and serum cortisol were measured before and after non-occlusive treatment of two weeks, using 0.01 percent fluorocorticoids and controls after 24 hours and 8 days. A significant drop of the 17-keratogenicsteroids was found in patients studied at the end of the treatment, with immediate recovery. Additionally it was observed, in patients who had over 30 percent of skin area involved, that there was a decrease in serum cortisol, which persisted even 24 hours after discontinuing treatment, with normal levels in a measurement taken eight days later. It is therefore concluded that glucocorticoids applied topically are capable of inhibiting adrenal function.

17-Ketosteroids↗