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Biomedical subjects

J A Barnes

Publications and source records attributed to J A Barnes.

At least 37 records · Page 2Linked to original sources
PubMed1997

Towards a strategy for learning: the response of practices to the Liverpool pilot scheme for extramural study.

This paper presents the responses of veterinary surgeons to a pilot scheme initiated by the SILVER project. The scheme was designed to increase communication between a veterinary school, host practices and students undertaking extramural study ("seeing practice') and to provide a more structured use of the students' time. The work is set in the context of recent interest in work-based learning as part of undergraduate education, the approach being based on experience gained from a number of professions, including veterinary science. Students were required to identify and communicate their personal learning objectives to host practices in advance of their arrival, and practices were asked to collaborate in a new system for recording students' progress. The paper presents an analysis of the evidence obtained from questionnaires sent to pilot practices. It shows that all the elements of the scheme had been received favourably and had had a positive impact on student learning. The findings are discussed in relation to the development and implications of an educational strategy for extramural study.

Education, Veterinary↗
PubMed1997

Immunolocalization and heart levels of GRP94 in the mouse during post-implantation development.

Glucose-regulated proteins (GRPs), which belong to the highly conserved family of stress proteins, are resident to the endoplasmic reticulum and function as molecular chaperones. Heat shock proteins have been shown to be developmentally regulated, but little work has been done to investigate the expression of GRPs during embryogenesis. Therefore, this study examined the distribution of GRP94 within mouse embryos during the period of organogenesis and characterized levels of GRP94 within the developing heart during organogenesis and late fetal stages. Our results demonstrate that the GRP94 protein is constitutively expressed within mouse embryos during early stages of organogenesis and is localized particularly within the developing heart, neuroepithelium, and surface ectoderm tissues. Positive staining for GRP94 remains within developing heart tissues throughout organogenesis and is found primarily within the atrial and ventricular myocardial cells. Western blot analysis of GRP94 expression demonstrates a significantly higher level of GRP94 in embryonic hearts during early stages of organogenesis than in later stages of organogenesis or the fetal period. These results demonstrate that the stress protein GRP94 is constitutively expressed within specific tissues during post-implantation mouse development and suggest that GRPs may play an important role in the process of myocardial cell differentiation and heart development.

Animals↗
PubMed1997

Major proteins of yam bean tubers.

The tuberous roots of the Mexican yam bean, jicama, (Pachyrhizus erosus L. Urban) contained large quantities of two acidic glycoproteins which accounted for more than 70% of the total soluble proteins (about 3 g per 100 g of tuber on a dry weight basis). The two major proteins, tentatively named YBG1 and YBG2, had apparent M(r)s of 28,000 and 26,000, respectively, by SDS-PAGE. A third protein named YBP22 which accounted for 2-5% of the total soluble proteins had an M(r) of 22,000. YBG1 and YBG2 exhibited great similarity on the basis of their amino acid composition and had identical N-terminal amino acid sequences. The first 23 amino acids in the N-terminal region of YBG2 were DDLPDYVDWRDYGAVTRIKNQGQ which showed strong homology with the papain class of cysteine proteases. YBG1 and YBG2 were found to bind to a Concanavalin A-Sepharose column and were also stained positively by a sensitive glycoprotein stain. Both glycoproteins exhibited cysteine proteolytic activity. In contrast, YBP22 showed sequence homology with several known protease inhibitors, and a polyclonal antibody raised against this protein cross reacted with soybean trypsin inhibitor.

Amino Acid Sequence↗
PubMed1997

Protein phosphatases are pest containing proteins.

Protein phosphatases are required for removing phosphoryl groups in proteins involved in many physiological processes. Investigation of these enzymes for regions rich in proline (P), glutamic acid (E), serine (S) and threonine (T), called PEST regions showed that greater than 85% of the phosphatases investigated contained these regions. These regions are believed to be signals for degradation and could possibly serve as regulators of the intracellular localization and catalytic activity via limited proteolysis or as conditional signals for rapid degradation of these proteins by the ATP/ubiquitin-dependent and/or the ATP non-ubiquitin dependent proteolytic pathway. Many of these phosphatases were also found to contain a pentapeptide sequence biochemically related to the KFERQ motif which targets proteins for lysosomal degradation which suggest that several pathways may exist for the degradation of protein phosphatases.

Amino Acid Sequence↗
PubMed1995

Pest sequences in EF-hand calcium-binding proteins.

Calcium binding proteins are subdivided into two major families: the EF-family and the Annexin family. The EF-hand family is distinguished by the characteristic helix-loop-helix motif which consists of two alpha-helices separated by a loop. The EF-hand Ca2+(-)binding protein family contain subfamilies rich in proline, glutamic acid, serine and threonine residues (called PEST sequences) and non PEST-containing subfamilies. A few of the Ca2+(-)binding proteins contain KFERQ-like sequences which are thought to be possible signals for lysosomal degradation. Arginine pairs (RR) which have also been suggested to act as signals for proteolysis were found to be few or absent. However, most EF-hand proteins were found to possess lysine pairs (KK) which may also act as signals for proteolysis.

Amino Acid Sequence↗
PubMed1993

Structural and functional characterization of the HPV16 E7 protein expressed in bacteria.

The E7 gene of the human papillomaviruses (HPV) encodes a 98-amino acid, multifunctional nuclear phosphoprotein with functional and structural similarities to adenovirus E1A and the papovavirus T antigens. E7 is a viral oncoprotein, which will cooperate with an activated ras oncogene to transform primary rodent cells, and can cooperate with the HPV E6 protein for the efficient immortalization of primary human keratinocytes. Due to the compelling epidemiological and experimental association between HPV infection and cervical cancer, we have undertaken a detailed study of the structure of the HPV16 E7 protein. The E7 protein was expressed in Escherichia coli as a native, unfused polypeptide, and soluble protein was purified by conventional chromatographic techniques. The purified protein was assessed for various biochemical and biophysical properties. Purified E7 binds the retinoblastoma protein avidly and specifically, and it can dissociate the E2F transcription factor when assayed in vitro. Circular dichroism spectroscopy indicated that E7 reversibly binds Zn2+ and Cd2+, resulting in a substantial increase in the alpha-helical content of the metal-bound E7 consistent with the stabilization of a hydrophobic core in the COOH terminus of the protein.

Amino Acid Sequence↗
PubMed1993

Separation of pyridinecarboxylic acid isomers and related compounds by capillary zone electrophoresis. Effect of cetyltrimethylammonium bromide on electroosmotic flow and resolution.

The effect of the addition of cetyltrimethylammonium bromide (CTAB) to the buffer system in capillary electrophoresis on electroosmotic flow (EOF) is examined. At a CTAB concentration of 2.5 x 10(-4) M, EOF is anodal (flow towards the positive detector column end). With bare silica columns, anodal EOF first increases with increasing pH, up to a maximum in the pH range 4-6 depending on CTAB concentration, then decreases as pH is further increased. Optimum resolution of pyridinecarboxylic acid isomers is obtained at pH 2.7 with a 10 mM phosphate buffer and 30 mM CTAB. Using the same buffer system, optimum resolution for hydroxy-substituted pyridinecarboxylic acid isomers is obtained at pH 7.5. The use of CTAB results in a dramatic improvement in peak shape. Preliminary results, using an excimer laser operated at 248 nm, show that the fluorescence intensity of isonicotinic acid is substantially enhanced with the addition of 0.3% hydrogen peroxide to the phosphate buffer system.

Cetrimonium↗
PubMed1992

Novel bovine heart calmodulin-dependent protein kinase which phosphorylates a high molecular weight calmodulin-binding protein.

A novel calmodulin-dependent protein kinase has been isolated from bovine cardiac muscle by successive chromatography on DEAE-Sepharose 6B, Calmodulin-Sepharose 4B affinity and Sepharose 6B chromatography columns. The protein kinase was shown by gel filtration chromatography to have a molecular mass of 36,000 daltons. The highly purified protein kinase stoichiometrically phosphorylated the high molecular weight calmodulin-binding protein from cardiac muscle [Sharma RK (1990) J Biol Chem 265, 1152-1157] in a Ca2+/calmodulin-dependent manner. The phosphorylation resulted in the maximal incorporation of 1 mol of phosphate/mol of the high molecular weight calmodulin-binding protein. Other Ca2+/calmodulin-dependent protein kinases failed to phosphorylate the high molecular weight calmodulin-binding protein. The distinct substrate specificity of this protein kinase indicates that it is not related to the known calmodulin-dependent protein kinases and therefore constitutes a novel protein kinase.

Animals↗
PubMed1992

Structure-function analysis of the human papillomavirus type 16 E7 oncoprotein.

The E7 gene of human papillomavirus type 16 encodes a multifunctional nuclear phosphoprotein that is functionally and structurally similar to the adenovirus (Ad) E1A proteins and the T antigens of other papovaviruses. E7 can cooperate with an activated ras oncogene to transform primary rodent cells, trans activate the Ad E2 promoter, and abrogate transforming growth factor beta-mediated repression of c-myc. Recent studies suggest that these functions may in part be a consequence of the ability of E7 to associate with the product of the retinoblastoma tumor suppressor gene (pRB). In this study, a series of site-specific mutations of the human papillomavirus type 16 E7 gene product were constructed and assessed for their effects on intracellular protein stability, ras cooperativity, transcriptional trans activation, pRB association, and phosphorylation. The results of these studies indicate that the transforming and trans-activating domains extensively overlap within a region of the protein analogous to conserved region 2 of Ad E1A, suggesting that pRB binding is necessary for both activities. Deletion of sequences in conserved region 1 abrogates cellular transformation but has only a marginal effect on trans activation. These data suggest that E7 trans activation and cellular transformation are interrelated but separable functions.

Amino Acid Sequence↗
PubMed1991

Analysis of trans activation by human papillomavirus type 16 E7 and adenovirus 12S E1A suggests a common mechanism.

The human papillomavirus E7 gene product is an oncoprotein with properties similar to those of the adenovirus E1A proteins. The human papillomavirus E7 proteins possess substantial amino acid sequence similarity to portions of conserved regions 1 and 2 of E1A, and the human papillomavirus type 16 E7 protein trans-activates the adenovirus E2 early promoter. Analysis of point mutations in the E2 promoter indicated that the E2F recognition sites were critical to E7 stimulation. In contrast to the activation of the E2 promoter, E7 could not trans-activate various other E1A-inducible promoters. Although the promoter specificity for E7 differs from that of 13S E1A trans activation, it is very similar to activation by the E1A 12S product. Moreover, analysis of the E7 protein has suggested that amino acid sequences critical for trans activation include those shared with E1A within conserved region 2. Biochemical studies demonstrate that the E7 protein, like the 12S E1A product, can alter the interaction of cellular factors with the E2F transcription factor. We therefore conclude that E7 trans activation is functionally related to that mediated by the 12S E1A product.

Adenovirus Early Proteins↗
PubMed1989

Conformation and stability of Sendai virus fusion protein.

The conformation and stability of Sendai virus fusion (F) protein were studied by circular dichroism spectroscopy, and the protein predictive models of Chou and Fasman and Robson and Suzuki were used to elucidate the secondary structure of Sendai virus F protein. The F protein conformation is predicted to contain 33% alpha-helix, 53% beta-sheet and 15% beta-turn by the Chou and Fasman model, and 30% alpha-helix, 55% beta-sheet, 9% beta-turn and 7% random coil by the Robson and Suzuki model. C.d. studies of F protein purified in the presence of the non-ionic detergent, n-octylglucoside, indicated the presence of 49% alpha-helix and 31% beta-sheet at pH 7.0, 54% alpha-helix and 28% beta-sheet at pH 9.0 and 50% alpha-helix and 23% beta-sheet at pH 5.4. A small change in conformation of the protein occurred when the pH was titrated from 7.0 to 5.4 and from 7.0 to 9.0 and a more pronounced conformational change occurred when the pH was changed from 9.0 to 5.4. The F protein in 0.2% n-octylglucoside was resistant to denaturation by 4 M guanidine hydrochloride, the reducing agent 20 mM mercaptoethanol, and to increases in temperature from 5 to 80 degrees C. Monoclonal anti-F protein antibody showed an increased binding to whole virus when the pH was changed from 7.0 to 9.0. The antibody binding was decreased when the pH was shifted from 9.0 to 5.4 Maximum haemolytic activity was observed with virus that was preincubated at pH 8.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1988

Lithium battery hazard: old-fashioned planning implications of new technology.

Lithium battery technology has important military applications and will increasingly enter the civilian marketplace. In order to prevent explosive fragmentation under some circumstances of malfunction or misuse, lithium batteries are designed to vent externally in the event of malfunction. Depending on the chemistry and size of a venting lithium battery, the release of toxic gases such as sulfur dioxide or thionyl chloride may pose risks to exposed individuals, particularly in enclosed spaces. Chemical and thermal burns, laryngeal edema, pulmonary edema, and bronchiolitis obliterans are potential outcomes. A case report is presented which illustrates the hazards. The hazards are not from unpredictable outcomes, but from failure to plan for predictable outcomes.

Accidents, Occupational↗
PubMed1987

Complete nucleotide sequence of the tick-borne, orthomyxo-like Dhori/Indian/1313/61 virus nucleoprotein gene.

The complete nucleotide sequence of the fifth largest segment of single-stranded RNA of the tick-borne, orthomyxo-like Dhori/Ind/1313/61 virus was determined by using cloned cDNA derived from infected cell mRNA and dideoxynucleotide sequencing of viral RNA. The fifth RNA contains 1479 nucleotides and can code for a protein of 477 amino acids with a molecular weight of 53,679 Da. The RNA 5 protein of the Dhori/Ind/1313/61 virus possesses five short regions (16-26 amino acids) which share a high degree (50-59%) of amino acid sequence homology with a computer-aligned consensus sequence of the influenza nucleoprotein gene family. These and other structural features of the RNA 5 protein suggest that RNA 5 of Dhori viruses codes for the nucleoprotein. The data also suggest that Dhori viruses are orthomyxoviruses, but that they are more distantly related to the influenza viruses than type A, B, and C viruses are to each other.

Base Sequence↗