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Biomedical subjects

J R Walker

Publications and source records attributed to J R Walker.

At least 109 records · Page 6Linked to original sources
PubMed1989

Forecasting aggregate period-specific birth rates: the time series properties of a microdynamic neoclassical model of fertility.

"This article demonstrates the value of microdata for understanding the effect of wages on life cycle fertility dynamics. Conventional estimates of neoclassical economic fertility models obtained from linear aggregate time series regressions are widely criticized for being nonrobust when adjusted for serial correlation. Moreover, the forecasting power of these aggregative neoclassical models has been shown to be inferior when compared with conventional time series models that assign no role to wages. This article demonstrates that, when neoclassical models of fertility are estimated on microdata using methods that incorporate key demographic restrictions and when they are properly aggregated, they have considerable forecasting power." Data are from the 1981 Swedish Fertility Survey.

Birth Rate↗
PubMed1989

Proposed method of well-child care in a resident's clinic.

Uniformity in a teaching hospital's pediatric outpatient clinic is often inconsistent because of the varying numbers of housestaff involved in patient evaluation. We have developed a flow sheet that defines the appropriate standards of care to be delivered at the Doctors Hospital Pediatric Outpatient Clinic. This flow sheet encompasses a method of rapid assessment of growth, development, physical examination, immunization status, screening laboratory testing, and parental education. We have defined these parameters as the minimal evaluation to be completed at each preschool well-child visit.

Child Health Services↗
PubMed1988

Management of anxiety and panic attacks in immediate care facilities.

The records of all patients entering the Emergency Department of a large general hospital and an adjacent walk-in medical clinic were reviewed for a 4-week period. Information was gathered on the assessment and treatment of patients given a final diagnosis of anxiety or panic disorder. The majority of patients receiving these diagnoses in both settings presented with physical complaints. In the Emergency Department, where psychiatric consultation services were available, psychiatric appointments were arranged for 80% of patients with anxiety as an entrance complaint and none of those with physical entrance complaints.

Anxiety Disorders↗
PubMed1988

Fatal acquired cytomegalovirus infection in a neonate with maternal antibody.

An extremely premature infant was born to a mother who had antibodies to cytomegalovirus (CMV). Despite having acquired transplacental antibodies, the baby developed an episode of presumed CMV hepatitis at the age of 10 weeks after blood transfusions from seropositive donors. Although the hepatitis settled, the baby developed chronic lung disease from which he died at the age of 5 months. Post mortem, widespread infection with CMV was demonstrated. The fact that serious CMV infection can develop in an infant of a seropositive mother further justifies the routine use of blood from CMV-negative donors for all transfusions given to infants of low birth weight.

Antibodies, Viral↗
PubMed1988

Effect of supplemental potassium in the receiving diet and form of antibiotic on feeder pig performance.

In five separate trials 901 feeder pigs (769 purchased and 132 university-raised) were used to determine the effect of level of dietary K (.64 vs 1.00 vs 1.40%), form of neoterramycin (feed-grade vs water-soluble) and a long-lasting oxytetracycline injection on subsequent performance. Purchased pigs fed a 28-d receiving diet with 1.00% K gained faster (P less than .05) than the control pigs fed a .64% K diet (.64 vs .60 kg) during a 1980 summer trial. Feed efficiency was not affected by level of dietary K. Three additional trials conducted during January, July and October of 1981 failed to substantiate this beneficial effect on rate of gain. Feeder pig performance was not different (P greater than .05) when either feed-grade or water-soluble neoterramycin was used as a 14-d receiving treatment at preventative levels. However, in one trial nearly twice as many pigs on the medicated feed diet required additional treatment for sickness compared with pigs receiving water medication (14.5 vs 7.9%; P less than .1). Giving pigs an injection of a long-lasting oxytetracycline (LA-200) either at the market or upon arrival at the finishing facility had no effect on performance; however, the pigs were home-raised rather than purchased; consequently, their health was excellent.

Animals↗
PubMed1987

Relation of the Escherichia coli dnaX gene to its two products--the tau and gamma subunits of DNA polymerase III holoenzyme.

The Escherichia coli DNA polymerase III holoenzyme 71.1 kDa tau subunit is a 643 amino acid protein encoded by the dnaX gene. This gene also encodes the holoenzyme 56.5 kDa gamma subunit. The tau factor (as a tau'-LacZ' fusion protein) has been isolated and shown to be cleaved in vitro to form gamma and a 135 kda C-terminal cleavage product. The tau'-LacZ' fusion protein, gamma, and the C-terminal cleavage product have been isolated. N-terminal sequencing has demonstrated that tau and gamma share the same N-terminal sequences and that tau is proteolytically cleaved in vitro between residues 498 and 499 to form gamma. In addition, residues 420-440 were shown to be present in both tau and gamma by use of antibody specific for a synthetic peptide corresponding to that sequence. Some mechanism functions in vivo to ensure that tau and gamma are synthesized in a ratio of about one-to-one, as shown by radioimmune precipitation of tau and gamma from cellular extracts.

Bacterial Proteins↗
PubMed1987

Indium-111-radiolabeled guinea pig peripheral leukocytes. In vivo distribution and response to leukotriene B4.

The preparation of indium-111 tropolonate-radiolabeled guinea pig peripheral mixed white cells (greater than 80% neutrophils) is described. Autologous rather than homologous cells are required to provide a population of labeled, functional cells on reintroduction to the animals. Surgery has been shown to result in a profound neutropenia from which the animals must recover before removal of blood for cell preparation. The response of radiolabeled cells parallels that of the unlabeled cell population to a chemotaxin, leukotriene B4. This material causes a profound neutropenia of rapid onset accompanied by a parallel fall in blood radioactivity. The fall in circulating radiolabel is accompanied by an increase in radioactivity in the thoracic region. These changes have been monitored externally using an automated isotope monitoring system.

Animals↗
PubMed1987

Escherichia coli DnaX product, the tau subunit of DNA polymerase III, is a multifunctional protein with single-stranded DNA-dependent ATPase activity.

The dnaZX gene of Escherichia coli directs the synthesis of two proteins, DnaZ and DnaX. These products are confirmed as the gamma and tau subunits of DNA polymerase III because antibody to a synthetic peptide present in both the DnaZ and DnaX proteins reacts also with the gamma and tau subunits of holoenzyme. To characterize biochemically the tau subunit, for which there has been no activity assay, the dnaZX gene was fused to the beta-galactosidase gene to encode a fusion product in which the 20 C-terminal amino acids of the DnaX protein (tau) were replaced by beta-galactosidase lacking only 7 N-terminal amino acids. The 185-kDa fusion protein, which retained beta-galactosidase activity, was overproduced to the level of about 5% of the soluble cellular protein by placing the gene fusion under control of the tac promoter and Shine-Dalgarno sequence. The fusion protein was isolated in one step by affinity chromatography on p-aminobenzyl 1-thio-beta-D-galactopyranoside-agarose. The purified fusion protein also had ATPase (and dATPase) activity that was dependent on single-stranded DNA. This activity copurified with the beta-galactosidase activity not only through the affinity column but also through a subsequent gel filtration. We conclude that the DnaX protein function involves binding to single-stranded DNA and hydrolysis of ATP or dATP, in addition to binding to other DNA polymerase III holoenzyme components, increasing the processivity of the core enzyme, and serving as a substrate for the production of the gamma subunit.

Adenosine Triphosphatases↗
PubMed1986

Nucleotide sequence of the Escherichia coli replication gene dnaZX.

The Escherichia coli 2.2 kilobase dnaZX region contains one 1929 nucleotide reading frame which directs the synthesis of two protein products involved in DNA polymerization. The larger consists of 643 amino acids in a deduced 71,114 dalton chain which could be the tau subunit of DNA polymerase III. The smaller, the DNA polymerase III gamma subunit, is encoded by the same reading frame as the larger. The dnaZX sequence contains a region homologous to ATP binding sites, suggesting that these replication factors are adenine nucleotide binding proteins.

Amino Acid Sequence↗
PubMed1986

The E. coli dnaY gene encodes an arginine transfer RNA.

The E. coli dnaY gene product is an arginine tRNA. Its 77 nucleotide sequence can be folded into a typical cloverleaf structure with a UCU anticodon corresponding to the rare arginine codon AGA. A dnaY+ plasmid confers overproduction of at least one arginine-accepting minor species of tRNAArg. The dnaY promoter was identified by run-off transcription studies, and the initiating nucleotide was identified by sequencing the 5' end of the in vitro transcript. The primary products in vitro are RNAs of 180 and 190 nucleotides, which presumably are processed in vivo to generate the mature form. Transcription is terminated in vitro, and presumably in vivo, by a rho-dependent process.

Arginine↗
PubMed1986

Compression of nucleic acid and protein sequence data.

This paper describes the application of text compression methods to machine-readable files of nucleic acid and protein sequence data. Two main methods are used to reduce the storage requirements of such files, these being n-gram coding and run-length coding. A Pascal program combining both of these techniques resulted in a compression figure of 74.6% for the GenBank data-base and a program that used only n-gram coding gave a compression figure of 42.8% for the Protein Identification Resource database.

Algorithms↗
PubMed1986

Psychiatric residents' experience and career interest in geriatric psychiatry: implications for training programs.

A survey of residents' experience and career interest in geriatric psychiatry was carried out in Canadian training centres. Residents' exposure to specific training experiences in geriatric psychiatry has been steadily increasing, although a large proportion of residents continue to report insufficient amount of experience and supervision in this area. Residents viewed geriatric psychiatry as involving special skills and knowledge and half were in favour of a compulsory rotation in this area. Geriatric psychiatry was an infrequent career choice along with other areas of psychiatry that have had difficulty in recruiting. Alternative approaches to service provision and recommendations for meeting the manpower needs are discussed.

Attitude of Health Personnel↗
PubMed1985

Directional movement of cells in vivo and in vitro under the influence of 5-lipoxygenase inhibitors.

Five inhibitors of 5-lipoxygenase activity [phenidone, nordihydroguaiaretic acid (NDGA), BW755c, nafazatrom and the methyl ester of caffeic acid] have been compared with the cyclo-oxygenase inhibitor indomethacin as inhibitors of aggregation and chemotaxis by guinea-pig polymorphonuclear leukocytes. The results suggest that neither 5-lipoxygenase nor cyclo-oxygenase products are of significance in these in vitro assays. However, all of these compounds, with the exception of BW755c, significantly inhibited cell accumulation in an acute inflammatory model. These results cast doubt on the central importance of any individual arachidonic acid metabolite in the development of inflammation in vivo.

Animals↗
PubMed1985

Oxidative transformations of arachidonic acid in human dispersed lung cells: disparity between the utilization of endogenous and exogenous substrate.

Eicosanoid release from human dispersed lung cells (HDLC) containing ca 5% mast cells was studied before and after cell activation with ionophore A23187 or anti-IgE. Basal release of eicosanoids synthesized from endogenous arachidonate was measured by radioimmunoassay. In descending order of abundance the products were: 5-hydroxyeicosatetraenoic acid (5-HETE) greater than thromboxane B2 (TXB2) greater than prostaglandin F2 alpha (PGF2 alpha) approximately immunoreactive (i)-PGE2 greater than PGD2 greater than 6-keto-PGF1 alpha approximately i-LTC4. Stimulation of HDLC with ionophore A23187 or, after passive sensitization, with anti-IgE resulted in 2-10 fold increases in the generation of individual eicosanoids. In terms of net generation the most abundant products were PGD2 and TXB2 with either stimulus. Activation with A23187 caused net release of i-LTC4 and 5-HETE, but these products were not measured after immunological activation. A more complete profile of lipoxygenase products released from HDLC dispersed from one lung was obtained after separation by high performance liquid chromatography combined with ultra violet spectroscopy and bioassay. The major products released from the cells from this lung with ionophore stimulation were 13-hydroxylinoleic acid greater than LTB4 greater than 5-HETE greater than 12-HETE greater than LTC4 greater than 15-HETE greater than 11-HETE approximately 9-HETE. When the utilization of exogenous [14C]-arachidonic acid for prostanoid biosynthesis was compared to that of endogenous unlabelled arachidonate the formation of TXB2 was consistently underestimated. These results imply compartmentalization of arachidonic acid utilization in Ca2+-activated HDLC. In unstimulated cells the proportional formation of PGD2 was overestimated when exogenous arachidonic acid was substrate. After activation with A23187 the proportions of PGD2 were similar with both substrate sources. The large proportions of PGD2 and TXB2 generated by HDLC further supports the view that these eicosanoids may be important inflammatory mediators in lung tissue.

Arachidonic Acid↗
PubMed1984

A rapid multi-component treatment for an obsessive-compulsive disorder.

A 67-yr-old woman with a 45-yr history of obsessive-compulsive problems related to fear of contamination was treated rapidly by a multi-component intervention. Questionnaire data following treatment showed the patient to be free of obsessive-compulsive complaints, and these were corroborated by behavioral observations. Follow-up probes conducted 6, 12 and 18 months later revealed continued maintenance of treatment gains. Patient-therapist contact time totalled 6 hr, about one-third of the time employed by Marks for exposure and response prevention, indicating the cost-effectiveness of a multi-component treatment intervention.

Aged↗