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Biomedical subjects

D F Smith

Publications and source records attributed to D F Smith.

At least 127 records · Page 7Linked to original sources
PubMed1994

Type A personalities tend to have low platelet monoamine oxidase activity.

This study investigated whether there are relations between type A behaviours and the activity of monoamine oxidase (MAO) in blood platelets. Forty male nonsmokers completed the Jenkins Activity Survey (JAS) and had a blood sample drawn while at work. The JAS was scored in the traditional manner, yielding scores for ambitiousness (factor A), impatience (factor S), competitiveness (factor H) and job involvement (factor J). High scores on JAS scales were associated with low MAO activity in blood platelets; the correlation between platelet MAO activity and job involvement was significant. The findings agree with previous reports in showing relationships between MAO activity and certain personality traits and support the notion that low activity of MAO may contribute to sympathetic hyperreactivity in type A individuals.

Adult↗
PubMed1994

Demonstration of a novel UDPGalNAc:GlcNAc beta 1-4 N-acetylgalactosaminyltransferase in extracts of Schistosoma mansoni.

It was recently demonstrated that complex-type N-linked oligosaccharides in glycoproteins synthesized by Schistosoma mansoni contain the unusual terminal sequence GalNAc beta 1-4GlcNAc beta 1-2Man alpha 1-2R. This structure suggests that the parasite might contain a novel glycosyltransferase that can add GalNAc to terminal GlcNAc residues in N-linked oligosaccharides. This report describes an assay for this enzyme, designated UDPGalNAc:GlcNAc beta 1-4 N-acetylgalactosaminyltransferase (beta 1-4GalNAcT), and demonstrates the presence of the enzyme activity in schistosome extracts. As an acceptor for the beta 1-4GalNAcT, we prepared from human fibrinogen a truncated biantennary glycopeptide that contained terminal GlcNAc residues. When this acceptor was incubated with schistosome extracts in the presence of UDP-[3H]GalNAc, Mn2+, and detergent, [3H]GalNAc was transferred to the glycopeptide acceptor. Approximately 75% of the radioactivity in the product isolated by lectin affinity chromatography was recovered as [3H]GalNAc following hydrolysis; likewise, a majority of the isolated product was bound by immobilized Wisteria floribunda agglutinin, a lectin that binds to schistosome-derived oligosaccharides containing terminal beta 1-4-linked GalNAc residues. The activity of the beta 1-4GalNAcT in schistosome extracts was dependent on time, protein, and UDPGalNAc.

Adenosine Triphosphate↗
PubMed1994

Evaluation of abomasal outflow diversion as an experimental model of hypochloremic, hypokalemic metabolic alkalosis in lactating cows.

Four adult, lactating dairy cows were subjected to diversion (loss) of gastric contents through a T-shaped cannula placed in the cranial part of the duodenum just distal to the pylorus. Diversion was continued for 10 to 12 hours, at which point the cows were very weak and depressed. The volume of effluent during this period ranged from 37.3 to 46.8 L, with the largest volume being produced during the first four hours. All cows became dehydrated, with mean packed cell volume and total plasma protein concentration increasing 30% and 19.6%, respectively, but with only a slight increase in plasma creatinine concentration. Plasma Cl- concentrations decreased from a mean of 97.3 mEq/L at the beginning of diversion to a mean of 87.2 mEq/L at eight hours. This was followed by a plateau or slight increase in concentrations over the final hours of diversion. Plasma K+ concentration followed a similar pattern, decreasing from a mean of 3.9 mEq/L to a mean of 2.94 mEq/L at six hours, followed by increasing values until termination of diversion. No changes in plasma Na+ concentration were noted, except for a mild decrease in one cow. Plasma calcium concentrations decreased significantly, reaching 6.6 +/- 0.6 mEq/L at the end of diversion. Venous pH, plasma HCO3- concentration, and plasma base excess concentration increased during the first four to eight hours of diversion, followed by a gradual decline. Although a mild hypochloremic metabolic alkalosis resulted from diversion of abomasal outflow in all cows, substantiated by a mild increase in plasma strong ion difference, the changes observed were not as great as expected.(ABSTRACT TRUNCATED AT 250 WORDS)

Abomasum↗
PubMed1993

FKBP54, a novel FK506-binding protein in avian progesterone receptor complexes and HeLa extracts.

Avian progesterone receptor complexes contain five major co-purifying proteins, including hsp90, hsp70, and a 23-kDa protein. The other receptor-associated proteins, p50 and p54, share amino acid sequence similarities with a 52-59-kDa component (p59, hsp56, or FKBP52) of mammalian steroid receptor complexes that is also a member of the FK506-binding proteins (FKBP) family of immunophilins. We show here that p50, but not p54, cross-reacts with a rabbit antiserum prepared against human FKBP52. Both p50 and p54 bind an FK506 affinity resin at 0.5 M KCl, but only p50 binds efficiently in low salt conditions. Glycerol density gradient analyses show that both p50 and p54 exist predominantly in oligomeric complexes at low ionic strength. The poor retention of p54 on FK506 resin at low ionic strength compared with the high retention of p50 suggests that these proteins may largely exist in separate complexes and may interact with other proteins, such as progesterone receptor, in distinctive manners. In HeLa cell extracts, a 55-kDa FK506-binding protein, distinct from FKBP52, cross-reacts with anti-p54 antibody FF1. We conclude that p50 is avian FKBP52, whereas p54 and the 55-kDa human FF1 antigen are FKBP54, a novel immunophilin.

Animals↗
PubMed1993

Immunological modulation and evasion by helminth parasites in human populations.

Helminth parasites are highly prevalent in human communities in developing countries. In an endemic area an infected individual may harbour parasitic worms for most of his or her life, and the ability of these infections to survive immunological attack has long been a puzzle. But new techniques are starting to expose the diverse mechanisms by which these agents modulate or evade their hosts' defences, creating a dynamic interaction between the human immune system and the parasite population.

Animals↗
PubMed1993

Two FKBP-related proteins are associated with progesterone receptor complexes.

Unactivated steroid receptors are in heterooligomeric complexes that perhaps stabilize a partially folded receptor polypeptide prior to hormone-dependent activation. Hsp90 is a common receptor component and hsp70 is a component of progesterone receptors; both appear to be important as general mediators of protein folding and assembly events. In addition to hsp90, mammalian steroid receptor complexes contain a 52-59-kDa protein that is an FK506-binding immunophilin and has peptidyl-prolyl isomerase activity. Other receptor-associated proteins have been identified but not well-characterized. In the present study, we obtained partial amino acid sequences for two avian progesterone receptor components, p50 and p54. From sequence comparisons with known proteins, they appear to be distinct members of the FKBP family of immunophilins. Six p50 peptide sequences have 80% identity with regions of rabbit FKBP52; seven p54 peptide sequences have 60% identity with rabbit FKBP52. Interaction of p54 with receptor is distinct from p50 in that its binding in vitro is highly sensitive to progesterone or N-ethylmaleimide. An anti-p54 monoclonal antibody was developed that detects a 55-kDa protein in rabbit and human tissues; in a cell-free reconstitution system, the rabbit antigen binds to chicken progesterone receptor along with rFKBP52. While p50 appears to be the chicken homolog of FKBP52, p54 is perhaps a novel member of the FKBP family that, in addition to FKBP52, interacts with progesterone receptor.

Amino Acid Sequence↗
PubMed1993

Leishmania major: characterisation and expression of a cytoplasmic stress-related protein.

The DNA sequence of a single-copy gene from Leishmania major has been determined and shown to share sequence identity with eukaryotic heat shock protein-70-related genes. Conserved features of the deduced open reading frame include amino acids implicated in ATP binding and a putative calmodulin-binding domain. Antibodies generated to the recombinant fusion protein recognise a 70-kDa molecule of pI 6.0. This molecule is constitutively expressed and localises to the cytoplasm in all stages of the parasite life cycle.

Amino Acid Sequence↗
PubMed1993

Enhancement of Y-maze learning by piracetam, 2-thio-1-pyrrolidine-acetamide and 2-thio-1-pyrrolidine-thio-acetamide in rats.

Learning of rats given either piracetam, 2-thio-1-pyrrolidine-acetamide (thioacet) or 2-thio-1-pyrrolidine-thio-acetamide (thiothio) was studied in order to investigate nootropic effects of the compounds. Learning ability was measured using a Y-maze with water reward for the correct choice in a black-white discrimination task. Thioacet and thiothio enhanced learning ability of the rats at doses that were 2.5-10 times lower than those required for obtaining nootropic effects of piracetam. Thus the thio-derivatives of piracetam might be of value for studying mechanisms of action of nootropic drugs.

Animals↗
PubMed1993

The initial development of a health-related quality of life model as an outcome measure in epilepsy.

Patients with refractory epilepsy, despite no fixed physical deficit, are often socially and psychologically handicapped. Currently available outcome measures for epilepsy do not adequately address these manifestations or their influence on well-being and quality of life. A patient-based health-related quality of life (HRQL) model for epilepsy including physical, social and psychological domains was constructed. It contains previously validated measures of anxiety, depression, happiness, overall mood, self-esteem, mastery, social satisfaction and general health and a specifically designed seizure severity scale with patient- and carer-based components. The psychometric properties of this model were evaluated in the context of the trial of a potential new antiepileptic drug. All the scales, except the Social Problems Questionnaire, have acceptable internal consistency (alpha 0.69-0.85) in this patient population. Construct validity is indicated by the ability of the scales to differentiate between groups of patients predicted to have different levels of psychosocial function. Treatment effects were detected by the patient (P = 0.017) and carers (P = 0.035) subscales of the seizure severity scale, the happiness (P = 0.003) and the mastery (P = 0.003) scales. Despite obvious deficiencies preliminary analyses are encouraging. This model provides a framework for investigating the complex interaction between the physical, social and psychological manifestations of epilepsy. The model has potential as an outcome measure for use in longitudinal studies and as a measure of disability for use in cross-sectional studies designed to compare quality of life in different populations of people with epilepsy.

Activities of Daily Living↗
PubMed1993

Comparison of chemiluminescence and ultraviolet ozone monitor responses in the presence of humidity and photochemical pollutants.

The effect of water vapor and other pollutants on ozone monitoring instruments was investigated. Five UV-type and two chemiluminescence-type monitors were employed in this study. The results of the study indicate that in systems containing ozone, water vapor and zero air only, the UV-based monitors showed negligible effects due to humidity. On average, the UV monitors were within 0.5 percent of independently determined ozone values judged to be extremely accurate. The chemiluminescence-based monitors showed systematically higher readings than the UV monitors with added water vapor. The effect was found to be linear with water vapor concentration with an average positive deviation of 3.0 percent per percent H2O at 25 degrees C. For these measurement, ozone concentrations ranged from 85 to 320 ppbv and water concentrations from 1 to 3 percent (i.e., dew point temperatures from 9 to 24 degrees C). These results are largely in agreement with previous studies conducted to measure this interference, although the present study extends the range of water concentrations tested. Studies were also performed with a smog chamber with simulated polluted air (containing paraffinic, olefinic and aromatic hydrocarbon precursors) and varying relative humidities. Although the presence of water vapor did not appear to represent a substantial interference in these systems, a positive interference was observed with the UV monitors. This interference was likely a result of the presence of toluene and some of its aromatic photooxidation products (e.g., benzaldehyde), which can be partially removed from the reference stream by the ozone scrubber within the UV monitor. If the compound absorbs radiation at 254 nm, it is detected as ozone. However, when the results are scaled back to ambient concentrations of toluene and NO(x), the effect appears to be very minor (ca. 3 percent under the study conditions). It is concluded that under atmospheric conditions at moderate pollution and relative humidity levels, both types of instruments can give accurate measurements of the ozone concentration. These potential effects should be recognized when conducting ambient ozone measurements.

Journal Article↗
PubMed1993

Analysis of mosquito bloodmeals by DNA profiling.

Human specific genetic markers have been used to profile the human DNA found within a mosquito bloodmeal. In this technique, variable numbers of tandem repeat (VNTR) sequences are employed to prime amplification of human DNA in the polymerase chain reaction (PCR) and the radiolabelled products are analysed by high resolution denaturing gel electrophoresis. Matching of DNA profiles allows identification of the individual human host. Bloodmeals of 125 female Anopheles gambiae Giles mosquitoes, caught dead or alive in verandah-trap huts wherein two people had slept overnight protected by intact insecticide-impregnated bednets, were analysed: thirty-five out of thirty-nine profiles generated were identical to those of the sleepers under the nets. Thus the blood-fed mosquitoes found after impregnated nets have been used cannot, in most cases, be explained away by entry of already fed mosquitoes into the huts.

Animals↗
PubMed1993

Coronary-prone behavior may be declining in Danish men and women.

Four hundred males and four hundred females were randomly selected from the Danish population and received the Jenkins Activity Survey (JAS) on two occasions, once in 1988 and again in 1992. The JAS was rated by the standard procedure, providing a measure of the degree of time urgency and ambitiousness (Factor A), speed and impatience (Factor S), hard-driving and competitiveness (Factor H) and job involvement (Factor J) shown by the subjects. The scores obtained for all four factors tended to be lower in 1992 than in 1988, and the differences were significant for Factor H. In addition, gender differences were observed for Factors A, S and J, with higher scores being obtained by males than by females. Age-related differences were observed for Factors A and J. The findings indicate that Type A behaviors have declined during the past four years in the Danish adult population and that different strategies may be required for encouraging health behaviors in men and women.

Adult↗
PubMed1993

Identification of a 60-kilodalton stress-related protein, p60, which interacts with hsp90 and hsp70.

Immunoaffinity purification of hsp90 from chick oviduct cytosol reveals two major proteins, hsp70 and a 60-kDa protein (p60), copurifying with hsp90. A similar result is obtained when hsp90 is immunoaffinity purified from chick liver and brain cytosols, avian fibroblasts, and rabbit reticulocyte lysate. This p60 is the same protein previously identified in certain assembly complexes of chick progesterone receptor generated in a cell-free reconstitution system. Tryptic and cyanogen bromide peptide fragments were generated from gel-purified p60, and partial N-terminal sequences were determined from eight peptides. The sequences show a striking similarity to the sequence of a 63-kDa human protein (IEF SSP 3521) whose abundance is increased in MRC-5 fibroblasts following simian virus 40 transformation. A monoclonal antibody was prepared against avian p60; Western immunoblot analysis showed that p60 was present in each of eight chick tissues examined and in each of the human, rat, rabbit, and Xenopus tissues tested. Immunoaffinity purifications from both chick oviduct cytosol and rabbit reticulocyte lysate using anti-p60 and anti-hsp70 monoclonal antibodies confirm that there is a relatively abundant complex in these extracts containing hsp90, hsp70, and p60. This complex appears to comprise an important functional unit in the assembly of progesterone receptor complexes. However, judging from the abundance and widespread occurrence of this multiprotein complex, hsp90, hsp70, and p60 probably function interactively in other systems as well.

Amino Acid Sequence↗
PubMed1993

Dynamics of heat shock protein 90-progesterone receptor binding and the disactivation loop model for steroid receptor complexes.

A cell-free system was used to examine heat shock protein 90 (hsp90)-progesterone receptor (PR) binding at near physiological conditions. Four major findings are presented: 1) hsp90 is required to maintain ligand binding by PR at elevated temperatures; 2) hsp70 and heat shock-related protein p60 are components of an intermediate assembly complex that precedes formation of a mature hsp90-PR complex; 3) hsp90-PR complexes are in a steady state assembly/disassembly cycle (t1/2, 5 min); and 4) hsp90 dissociation is not accelerated after progesterone binding; instead, progesterone prevents PR from forming hsp70-mediated assembly complexes. A model incorporating these findings is presented in which unliganded PR is maintained in a disactivation loop of assembly/disassembly with hsp90; hormone binding releases PR from this loop to proceed along an activation pathway.

Animals↗
PubMed1993

Expression of a mitochondrial stress protein in the protozoan parasite Leishmania major.

The DNA sequence has been determined of a gene from Leishmania major that shares sequence identity with members of the eukaryotic heat shock protein (hsp) 70 gene family. The deduced open reading frame for translation shares a number of features common to hsp70 stress proteins, including conserved amino acids implicated in ATP binding and a putative calmodulin-binding site. In addition, the protein has an N-terminal sequence characteristic of a mitochondrial targeting signal. Specific antibodies to this protein, generated by the use of recombinant fusion peptides, recognise a 65 kDa molecule of pI 6.7. This molecule is constitutively expressed and localises to the mitochondrion in all stages of the parasite life cycle. These features suggest a role for this protein as a molecular chaperone in Leishmania.

Amino Acid Sequence↗
PubMed1993

Assessing and treating decreased cardiac output.

The compensatory pathophysiological mechanisms for a decreased cardiac output are explored via three case studies. The assessments and nursing interventions appropriate to these patients are included in separate tables. Evaluation and decision making about the patient's clinical status and responses are major nursing responsibilities that require astute assessment and skilled intervention to lead to optimal patient outcomes.

Aged↗
PubMed1993

Comparison of 0.9, 3.6, and 7.2% NaCl for correction of experimentally induced hypochloremic, hypokalemic metabolic alkalosis in sheep.

Nine adult female sheep were each surgically fitted with an Ivan and Johnston reentrant cannula in the cranial part of the duodenum just distal to the pylorus. By diversion (loss) of abomasal outflow, this model has been shown to consistently induce hypochloremic, hypokalemic metabolic alkalosis, accompanied by hyponatremia and dehydration. Each sheep was subjected to 3 treatment trials, each preceded by a 24-hour prediversion period, and a diversion period during which a syndrome of hypochloremia (68 +/- 2 mEq/L), hypokalemia, hyponatremia, and metabolic alkalosis was induced. Development of this syndrome was attributable to losses of large amounts of acid and electrolytes in the abomasal effluent. Mean total electrolyte contents of the effluent were: Cl-, 650 +/- 27 mEq; Na+, 388 +/- 23 mEq; and K+, 123 +/- 12 mEq, with total volume loss ranging from 3.6 to 10.0 L of gastric contents and pH ranging from 3 to 5. Decreases in plasma electrolyte concentrations also can be attributed to decreased intake, because anorexia developed shortly after the onset of diversion. Electrolyte losses in urine during diversion were minimal for Cl- (mean +/- SEM, 12.0 +/- 5.1 mEq), but were greater for Na+ (124.2 +/- 14.5 mEq) and K+ (185.1 +/- 31.2 mEq). Treatments consisted of 0.9% NaCl (300 mosm/L), 3.6% NaCl (1,200 mosm/L), and 7.2% NaCl (2,400 mosm/L) administered over a 2-hour period, with the administered volume determined by the estimated total extracellular fluid Cl- deficit. Significant difference was not found among treatments, with all solutions resulting in return of clinicopathologic and physical variables to prediversion values within 12 hours of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Abomasum↗