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Biomedical subjects

J Bush

Publications and source records attributed to J Bush.

At least 37 records · Page 2Linked to original sources
PubMed1995

The role of food aid in drought and recovery: Oxfam's North Turkana (Kenya) drought relief programme, 1992-94.

Regional droughts carry the seeds of catastrophe: the immediate risk is famine; the long-term risk is destitution. Preventing both situations is an appropriate, if not essential, goal for relief agencies. In the past, responses to hunger in Turkana District (north-west Kenya) have taken the form of traditional feeding programmes. A better understanding of the boom/bust cycles in pastoralist systems has, however, produced new relief strategies. A central tenet of these strategies is the acceptance that relief aid should assume two roles: humanitarian--to overcome food deficits--and economic--to overcome 'income' deficits. Arguments in favour of a broader role for food aid are tested with a case study of a drought relief programme in north Turkana between 1992-1994. Field studies confirmed that when food aid is integrated as an asset into household resources, it can strengthen economic recovery. Ultimately, the extent to which relief operations are able to protect both people's lives and their livelihoods is the key to more sustainable development in drought-prone areas.

Adult↗
PubMed1994

Characterization of lysosomal membrane proteins of Dictyostelium discoideum. A complex population of acidic integral membrane glycoproteins, Rab GTP-binding proteins and vacuolar ATPase subunits.

Highly purified lysosomes, prepared by magnetic fractionation of homogenates from Dictyostelium discoideum cells fed colloidal iron, were lysed under hypoosmotic conditions, and the membrane-associated proteins were subjected to gel electrophoresis. Thirteen major membrane polypeptides, ranging in molecular weight from 25,000 to 100,000 were identified. The isoelectric points of these proteins ranged from below 3.8 to greater than 7.0. Most of these proteins were stripped from membranes exposed to a chaotropic agent, 3,5-diodo-2-hydroxybenzoic acid lithium salt, and were therefore classified as peripheral membrane proteins. Twenty five glycoprotein species were detected by lectin blot analysis; 19 were classified as integral membrane proteins, and were, in general, larger than 45 kDa and negatively charged due in part to the presence of mannose 6-sulfate. Western blot analysis also demonstrated that a Rab 4-like GTPase, a Rab 7-like GTPase, and at least three subunits of the vacuolar ATPase were associated with the lysosomal membrane; the ATPase subunits appeared to be major proteins in lysosomal membranes. Finally, based on N-terminal sequence analysis of a major 41-kDa lysosome-associated membrane protein, we cloned a cDNA that encodes a protein (DVA41) highly homologous to a yeast and a bovine vacuolar ATPase subunit of approximately 41 kDa. The D. discoideum DVA41 gene was apparently a single copy gene, expressed at constant levels during growth and development.

Adenosine Triphosphatases↗
PubMed1994

Molecular cloning and characterization of the full-length cDNA encoding the developmentally regulated lysosomal enzyme beta-glucosidase in Dictyostelium discoideum.

The developmentally regulated Dictyostelium discoideum lysosomal enzyme beta-glucosidase is synthesized as a membrane-associated glycosylated precursor polypeptide which undergoes at least two proteolytic cleavage events to generate a soluble mature lysosomally localized protein. To begin to analyze the mechanisms regulating the sorting of this protein and the regulation during development of the expression of the encoding gene, we have cloned and sequenced a 2.6-kilobase (kb) cDNA which contains a complete 2463-nucleotide open reading frame coding for beta-glucosidase. Conceptual translation of this open reading frame predicts a polypeptide similar in molecular mass to the primary translation product of 94 kDa that also contains the same amino acid sequences of two V8 protease derived-peptides generated from the purified beta-glucosidase enzyme. The D. discoideum enzyme contained regions highly homologous at the amino acid sequence level to both bacterial and fungal beta-glucosidases, although these regions did not overlap. A potential cleavable signal sequence was also found in the first 21 amino acids followed by a highly polar stretch of 49 amino acids which (based on amino acid sequencing of the mature beta-glucosidase) represents a pro region for this protein. This region is similar in location, size, and charge to the D. discoideum alpha-mannosidase pro-I region (Schatzle, J., Bush, J., and Cardelli, J. (1992) J. Biol. Chem. 267, 4000-4007). Several small hydrophobic stretches of amino acids were also distributed throughout the protein; however, no obvious transmembrane region(s) were identified which might explain the observed membrane association of the precursor protein. Finally, Northern blot analysis indicated that the gene encoding this enzyme was under developmental regulation. The steady state level of a 2.7-kb beta-glucosidase mRNA decreased significantly during the aggregation stage of development, from high levels during growth, and then increased in the form of a larger size 2.8-kb mRNA during the final stages of development.

Age Factors↗
PubMed1994

Attitude change amongst nursing students towards Australian aborigines.

A pre-test and post-test impact evaluation design was used to determine if attendance at a workshop conducted by Australian aboriginal health personnel improved the attitudes of nursing students towards Aborigines. A three-hour workshop attended by first year nursing students comprised an introduction, video and discussion. A self-administered questionnaire, consisting of socio-demographic background questions and attitude rating scale, was used to measure students' attitudes before and after the workshop. The Wilcoxon signed rank test and paired t-test were used to test for significant improvement in students' total attitude scores. Multiple regression analysis was conducted to determine if socio-demographic variables contributed to the changes in the students' attitude scores. Complete data were collected from 246 students. Results indicate improvement in attitude scores. Socio-demographic variables did not contribute to these scores.

Adult↗
PubMed1994

A Rab4-like GTPase in Dictyostelium discoideum colocalizes with V-H(+)-ATPases in reticular membranes of the contractile vacuole complex and in lysosomes.

In the course of screening a cDNA library for ras-related Dictyostelium discoideum genes, we cloned a 0.7 kb cDNA (rabD) encoding a putative protein that was 70% identical at the amino acid level to human Rab4. Rab4 is a small M(r) GTPase, which belongs to the Ras superfamily and functions to regulate endocytosis in mammalian cells. Southern blot analysis indicated that the rabD cDNA was encoded by a single copy gene while Northern blot analysis revealed that the rabD gene was expressed at relatively constant levels during growth and differentiation. Affinity-purified antibodies were prepared against a RabD fusion protein expressed in bacteria; the antibodies recognized a single 23 kDa polypeptide on western blots of cell extracts. Density gradient fractionation revealed that the RabD antigen co-distributed primarily with buoyant membranes rich in vacuolar protons pumps (V-H(+)-ATPases) and, to a lesser extent, with lysosomes. This result was confirmed by examining cell lines expressing an epitope-tagged version of RabD. Magnetically purified early endocytic vesicles and post-lysosomal vacuoles reacted more weakly with anti-RabD antibodies than did lysosomes. Other organelles were negative for RabD. Double-label indirect immunofluorescence microscopy revealed that RabD and the 100 kDa V-H(+)-ATPase subunit colocalized in a fine reticular network throughout the cytoplasm. This network was reminiscent of spongiomes, the tubular elements of the contractile vacuole system. Immunoelectron microscopy confirmed the presence of RabD in lysosome fractions and in the membranes rich in V-H(+)-ATPase. We conclude that a Rab4-like GTPase in D. discoideum is principally associated with the spongiomes of contractile vacuole complex.

Amino Acid Sequence↗
PubMed1994

Bringing the lab home with near-patient testing.

Near-patient testing has been shown to decrease costs while improving the quality of patient care. Technological advances are making this cost-effective element of caring more accessible.

Clinical Laboratory Techniques↗
PubMed1994

Isolation of two novel ras genes in Dictyostelium discoideum; evidence for a complex, developmentally regulated ras gene subfamily.

In Dictyostelium discoideum, three ras genes (rasD, rasG and rasB) and one ras-related gene (rap1) have been previously isolated and characterized, and the deduced amino acid sequence of their predicted protein products share at least 50% sequence identity with the human H-Ras protein. We have now cloned and characterized two additional members of the ras gene subfamily in Dictyostelium, rasC and rasS. These genes are developmentally regulated and unlike the previously isolated Dictyostelium ras genes, maximum levels of their transcripts were detected during aggregation, suggesting that the encoded proteins have distinct functions during aggregation. The rasC cDNA encodes a 189 amino acid protein that is 65% identical to the Dictyostelium RasD and RasG proteins and 56% identical to the human H-Ras protein. The predicted 194 amino acid gene product encoded by rasS is 60% identical to the Dictyostelium RasD and RasG proteins and 54% identical to the human H-Ras protein. Whereas RasD, RasG, RasB and Rap1 are totally conserved in their putative effector domains relative to H-Ras, RasC and RasS have single amino acid substitutions in their effector domains, consistent with the idea that they have unique functions. In RasC, aspartic acid-38 has been replaced by asparagine (D38N), and in RasS, isoleucine-36 has been replaced by leucine (I36L). In addition, both proteins have several differences in the effector-proximal domain, a domain which is believed to play a role in Ras target activation. In RasC, there is a single conservative amino acid change in the canonical sequence of the binding site for the Ras-specific monoclonal antibody Y13-259, and consequently, RasC is less immunoreactive with the antibody than either of the Dictyostelium RasD or RasG proteins. In contrast, RasS, which has three substitutions in the Y13-259 binding site, does not react with the Y13-259 antibody.

Amino Acid Sequence↗
PubMed1993

Cloning and characterization of five novel Dictyostelium discoideum rab-related genes.

Low-M(r) GTPases belonging to the Ras superfamily are known to regulate a wide range of cellular processes including cell proliferation, actin cytoskeleton organization, and vesicular trafficking along the secretory and endosomal/lysosomal pathway. We are studying the regulation of lysosomal and endosomal vesicular trafficking in the simple eukaryote, Dictyostelium discoideum. Using an oligodeoxyribonucleotide (oligo) encoding one of the most highly conserved amino acid (aa) regions found in the low-M(r) GTPases (important in GTP binding), we have cloned 18 new cDNAs encoding proteins belonging to the Ras superfamily. In this report, we describe the characterization of five of these cDNAs coding for proteins belonging to the Ypt1/Sec4/Rab family; mammalian members of this family have been shown to function in the regulation of vesicular trafficking. Two of the cDNAs, rab1A and rab1B, code for proteins highly homologous to mammalian Rab1. An additional cDNA, rabA, codes for a protein that is only 60% identical to Rab1 at the aa sequence level and probably represents a new member of the rab gene family. Finally, two cDNAs, rabB and rabC, code for novel proteins belonging to the Rab gene family that are no greater than 50% identical in aa sequence to any previously described member. Southern blot analysis indicated that rab1A and and rab1B belong to a small Dictyostelium family of at least five related genes, while rabA belongs to a different and smaller family of related genes. In contrast, rabB and rabC appear to be represented by single genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Cloning and characterization of seven novel Dictyostelium discoideum rac-related genes belonging to the rho family of GTPases.

Cellular processes including proliferation, organization of the actin cytoskeleton, vesicular traffic and secretion of proteins comprising the lysosomal/endosomal system are regulated by low-molecular-weight GTP-binding proteins of the Ras superfamily. However, to date only three Dictyostelium discoideum ras-like genes and two ypt-1/sec4-like genes have been identified and characterized. We report here the identification (using an oligodeoxyribonucleotide probe) of seven additional cDNAs coding for members highly related to the Rac proteins (Ras-related-C3 botulinum toxin substrate) which belong to the Rho (Ras homologous) family of GTPases. Three of these rac-related genes (rac1A, rac1B and rac1C) predict proteins with > 90% amino acid (aa) sequence identity with each other and > 80% identity to the human rac1 gene product, whereas the other members (racA, racB, racC and racD) predict proteins with 46-74% identity to the rac1 and rhoA gene products and to each other. The D. discoideum proteins were entirely conserved over the four regions known to be important for GTP binding and all contained the C-terminal CAAX aa motifs shared by other Rho proteins. Interestingly, the D. discoideum rac-related genes revealed unique patterns of expression during growth and development. For instance, the steady-state level of rac1 mRNA, encoded by three highly related genes, increased transiently during aggregation and then rapidly decreased. In contrast, the cellular abundance of mRNAs encoded by the other rac-like genes decreased at different rates and to different levels during development from the peak levels observed during growth. This suggests that the GTP-binding proteins encoded by these genes may play unique roles during the different stages of the D. discoideum life cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Characterization of the signal transduction pathways and cis-acting DNA sequence responsible for the transcriptional induction during growth and development of the lysosomal alpha-mannosidase gene in Dictyostelium discoideum.

The lysosomal alpha-mannosidase gene in Dictyostelium discoideum is representative of a small group of genes that are expressed under two different conditions: 1) immediately upon removal of the bacterial food source from exponentially growing cells at < 5 x 10(5) cells/ml (which also initiates the developmental cycle), and 2) when the concentration of a secreted glycoprotein termed the prestarvation response factor (PSF) reaches a critical threshold in cultures growing at densities > 5 x 10(5) cells/ml. In this report we show that transcription of the alpha-mannosidase gene induced by starvation did not require protein synthesis in axenic wild-type strains, whereas protein synthesis was required for the transcriptional induction observed in response to PSF. Northern blot analysis was also done using mRNA from G alpha 1 and G alpha 2 gene disruption mutants. These genes encode subunits of heterotrimeric G proteins found at the cell surface in growing cells and cells early in development. The pattern of alpha-mannosidase gene expression was normal in these mutants as well as in mutants unable to produce the secreted glycoprotein conditioned medium factor or the cAMP receptor-1 protein. These genes have been shown to regulate the expression of many genes during early development. Promoter analysis studies identified a 145-base pair sequence element containing a TTG box which was required for alpha-mannosidase transcriptional induction under both starvation conditions and in response to PSF. The TTG box identified is an important regulatory element in the promoter of another prestarvation response gene, the discoidin I gamma gene. A ts mutant was found to misregulate the expression of both discoidin I and alpha-mannosidase expression at restrictive temperatures. Taken together these results suggest that the prestarvation response genes may be coordinately regulated possibly through the TTG box.

Animals↗
PubMed1992

Molecular cloning and characterization of the structural gene coding for the developmentally regulated lysosomal enzyme, alpha-mannosidase, in Dictyostelium discoideum.

The gene coding for the Dictyostelium discoideum lysosomal enzyme, alpha-mannosidase, has been cloned and sequenced. To accomplish this, the mature 60- and 58-kDa subunits of the enzyme were purified and subjected to liquid-phase N-terminal amino acid sequencing. Sequence information was obtained for both of the mature subunits, and a 48-mer oligonucleotide was synthesized based on the determined amino acid sequence of the 58-kDa subunit. Using this oligonucleotide as a probe, an 8-kilobase HindIII fragment of genomic DNA was isolated and subjected to Sanger dideoxy DNA sequencing. The first 4400 nucleotides contained the complete alpha-mannosidase gene and 1100 nucleotides of 5'-flanking DNA. Primer extension analysis indicated that transcription begins at multiple sites -48 to -64 nucleotides upstream of the first nucleotide of the predicted translation initiation codon. A single open reading frame (ORF) of 3015 nucleotides was found that was interrupted by a single intron and that contained the amino acid sequences of the N termini of the two mature alpha-mannosidase subunits; a polyadenylation signal was also found just downstream of the termination codon. A potential cleavable signal sequence was identified in the first 22 amino acids of the predicted precursor protein, and two propeptide regions (Pro I and II) were identified that were immediately upstream of the N termini of the 60- and 58-kDa mature subunits, respectively. These propeptide regions are not present in the mature protein and are therefore predicted to be proteolytically removed as the membrane associated 140-kDa precursor is transported to lysosomes and processed to the soluble 60- and 58-kDa mature forms of the enzyme. In fact, potential proteolytic cleavage sites were identified flanking the Pro I and Pro II regions. Pro I, which immediately follows the signal sequence, consists of 18 amino acids, most of which are highly charged and hydrophilic residues, while Pro II, found in the central portion of the precursor, is very hydrophobic. While no obvious transmembrane regions were identified, several short hydrophobic amino acid stretches were found to be localized in and around the Pro II region, and these may be responsible for attachment of precursors to membranes.

Amino Acid Sequence↗
PubMed1991

Lesbians in currently aggressive relationships: how frequently do they report aggressive past relationships?

Findings are reported from a survey examining the frequency with which women in currently aggressive same-sex relationships also report aggressive past relationships involving female partners, male partners, or members of their family of origin. Particular attention is paid to victims who also used aggression and their perceptions of whether their aggressive behavior was self-defensive or mutually aggressive. Results indicate that about one-fourth of participants had been victims of aggression in current relationships, roughly two-thirds had been victimized by a previous male partner, and almost three-fourths had experienced aggression by a previous female partner. Among those reporting having been both victims and users of aggression, about one-fifth had used aggression in their current relationship, almost one-third used aggression with a previous male partner, and nearly two-thirds had used aggression with a previous female partner. A majority of victims who had also used aggression with a previous male partner characterized this use as self-defense, as compared to only 30% of those who had used aggression with a female partner. Instead, aggression in relationships involving a female partner was most frequently described as mutually aggressive in nature.

Adult↗
PubMed1984

Paediatric surveillance: performance review and the primary care team.

Primary care teams should state the aims of a preventive service and, through performance review, assess whether these aims have been achieved. The paediatric surveillance scheme in one practice is described, and the results of certain intermediate outcome measures are given.

Child, Preschool↗
PubMed1983

Thymus-independent immunogenicity in vitro of the divalent antigen DNP-polyethylene oxide.

Chemically simple and physically well-defined dinitrophenyl derivatives of polyethylene oxide (DNP-PEO) can be prepared in a wide range of forms and sizes. These materials were used to investigate the molecular basis of immunogenicity and the binding of the antigens to membrane-bound receptors. Both di- and multivalent DNP-PEO activate normal murine B lymphocytes to yield primary anti-DNP antibody response in vitro. The immunogenicity is dependent on the carrier chain length but independent of T cells. Responses comparable to those induced by DNP-conjugated polymerized flagellin are induced by divalent linear materials of medium molecular weights of about 60,000. A highly multivalent material is moderately immunogenic, but at much lower antigen doses than divalent materials. The carrier PEO does not affect B-cell responses to DNP-PEO or T-cell response to succinyl concanavalin A. Moreover, it shows no polyclonal mitogenicity at concentrations as high as 1 mg/ml. Studies of antigen binding to cell surface DNP receptors show that the strongly immunogenic materials of medium molecular weights have an appreciable tendency to bind bivalently and thus potentially to crosslink receptors. The binding of smaller, less immunogenic antigen appears predominantly monovalent.

Animals↗