Showing papers by "University of Manitoba published in 1994"

H1-receptor antagonists. Comparative tolerability and safety.

Abstract: First-generation histamine H1-receptor antagonists, such as diphenhydramine, triprolidine, hydroxyzine or chlorpheniramine (chlorphenamine), frequently cause somnolence or other CNS adverse effects. Second-generation H1-antagonists, such as terfenadine, astemizole, loratadine and cetirizine, represent a true advance in therapeutics. In manufacturers' recommended doses, they have a more favourable benefit/risk ratio than their predecessors with regard to lack of CNS effects, and do not exacerbate the adverse CNS effects of alcohol or other CNS-active chemicals. Rarely, some of the newer H1-antagonists may cause cardiac dysrhythmias after overdose or under other specific conditions. The concept of a risk-free H1-antagonist is proving to be an oversimplification. An H1-antagonist absolutely free from adverse effects under all circumstances is not yet available for use. The magnitude of the beneficial effects of each H1-antagonist should be related to the magnitude of the unwanted effects, especially in the CNS and cardiovascular system, and a benefit-risk ratio or therapeutic index should be developed for each medication in this class.

Premature p34cdc2 activation required for apoptosis

Abstract: Activation of the serine-threonine kinase p34cdc2 at an inappropriate time during the cell cycle leads to cell death that resembles apoptosis. Premature activation of p34cdc2 was shown to be required for apoptosis induced by a lymphocyte granule protease. The kinase was rapidly activated and tyrosine dephosphorylated at the initiation of apoptosis. DNA fragmentation and nuclear collapse could be prevented by blocking p34cdc2 activity with excess peptide substrate, or by inactivating p34cdc2 in a temperature-sensitive mutant. Premature p34cdc2 activation may be a general mechanism by which cells induced to undergo apoptosis initiate the disruption of the nucleus.

The Role of the Sigma Factor sigmas (KatF) in Bacterial Global Regulation

Abstract: The protein encoded by katF (also known as nur, appR, csi-2, abrD, and rpoS in various alleles) has been biochemically confirmed to be an alternate sigma transcription factor and renamed sigma S. Its synthesis is controlled transcriptionally and posttranscriptionally by as yet undefined mechanisms that are active well into stationary phase. sigma S controls a regulon of 30 or more genes expressed in response to starvation and during the transition to stationary phase. Proteins in the regulon, many of which have not been characterized, enhance long-term survival in nutrient-deficient medium and have a diverse group of functions including protection against DNA damage, the determination of morphological changes, the mediation of virulence, osmoprotection, and thermotolerance. Differential expression of subfamilies of genes within the regulon is effected by supplementary regulatory factors, working both individually and in combination to modulate activity of different sigma S-dependent promoters.

Microwave Horns and Feeds

Abstract: This book is devoted to describing the theory, design, performance and application of microwave horns and feeds for reflector. The first general treatment of feeds for reflector antennas, it describes design principles and methods of analysis.

Identification of a common hyaluronan binding motif in the hyaluronan binding proteins RHAMM, CD44 and link protein.

Abstract: We have previously identified two hyaluronan (HA) binding domains in the HA receptor, RHAMM, that occur near the carboxyl-terminus of this protein. We show here that these two HA binding domains are the only HA binding regions in RHAMM, and that they contribute approximately equally to the HA binding ability of this receptor. Mutation of domain II using recombinant polypeptides of RHAMM demonstrates that K423 and R431, spaced seven amino acids apart, are critical for HA binding activity. Domain I contains two sets of two basic amino acids, each spaced seven residues apart, and mutation of these basic amino acids reduced their binding to HA--Sepharose. These results predict that two basic amino acids flanking a seven amino acid stretch [hereafter called B(X7)B] are minimally required for HA binding activity. To assess whether this motif predicts HA binding in the intact RHAMM protein, we mutated all basic amino acids in domains I and II that form part of these motifs using site-directed mutagenesis and prepared fusion protein from the mutated cDNA. The altered RHAMM protein did not bind HA, confirming that the basic amino acids and their spacing are critical for binding. A specific requirement for arginine or lysine residues was identified since mutation of K430, R431 and K432 to histidine residues abolished binding. Clustering of basic amino acids either within or at either end of the motif enhanced HA binding activity while the occurrence of acidic residues between the basic amino acids reduced binding. The B(X7)B motif, in which B is either R or K and X7 contains no acidic residues and at least one basic amino acid, was found in all HA binding proteins molecularly characterized to date. Recombinant techniques were used to generate chimeric proteins containing either the B(X7)B motifs present in CD44 or link protein, with the amino-terminus of RHAMM (amino acids 1-238) that does not bind HA. All chimeric proteins containing the motif bound HA in transblot analyses. Site-directed mutations of these motifs in CD44 sequences abolished HA binding. Collectively, these results predict that the motif of B(X7)B as a minimal binding requirement for HA in RHAMM, CD44 and link protein, and occurs in all HA binding proteins described to date.

Distribution Theory of Runs: A Markov Chain Approach

Abstract: The statistics of the number of success runs in a sequence of Bernoulli trials have been used in many statistical areas. For almost a century, even in the simplest case of independent and identically distributed Bernoulli trials, the exact distributions of many run statistics still remain unknown. Departing from the traditional combinatorial approach, in this article we present a simple unified approach for the distribution theory of runs based on a finite Markov chain imbedding technique. Our results cover not only the identical Bernoulli trials, but also the nonidentical Bernoulli trials. As a byproduct, our results also yield the exact distribution of the waiting time for the mth occurrence of a specific run.

Inhibition of nuclear hormone receptor activity by calreticulin

Abstract: We have shown that a polypeptide of M(r) 60,000 (60K) that shares N-terminal homology with a calcium-binding protein, calreticulin, can bind to an amino-acid sequence motif, KXGFFKR, found in the cytoplasmic domains of all integrin alpha-subunits. The homologous amino-acid sequence, KXFFKR (where X is either G, A or V), is also present in the DNA-binding domain of all known members of the steroid hormone receptor family; amino acids in this sequence make direct contact with nucleotides in their DNA-responsive elements and are crucial for DNA binding. Here we show that both the 60K protein (p60), purified on a KLGFFKR-Sepharose affinity matrix, and recombinant calreticulin can inhibit the binding of androgen receptor to its hormone-responsive DNA element in a KXFFKR-sequence-specific manner. Calreticulin can also inhibit androgen receptor and retinoic acid receptor transcriptional activities in vivo, as well as retinoic acid-induced neuronal differentiation. Our results indicate that calreticulin can act as an important modulator of the regulation of gene transcription by nuclear hormone receptors.

The Pharmacology and Use of H1-Receptor-Antagonist Drugs

Abstract: The second-generation H1-antagonist drugs are supplanting their predecessors in the treatment of allergic rhinoconjunctivitis and chronic urticaria. Their use can be justified mainly on the basis of a more favorable risk-benefit ratio, because they are less toxic to the central nervous system. Future research into H1 antagonists should include additional dose-response studies in patients with allergic disorders, especially children and the elderly; objective studies of adverse effects; studies of topical mucosal application of H1 antagonists; and studies of H1-antagonist enantiomers and active metabolites. With the cloning of the gene encoding the H1 receptor and increased understanding of the precise structural requirements for H1-receptor activity, H1 antagonists with an even more favorable therapeutic index may be developed.

The discriminant validity of burnout and depression: A confirmatory factor analytic study

Abstract: Health care workers (N=307) completed measures of burnout and depression as part of a study of personal and occupational sources of distress. A confirmatory factor analysis provided support for differentiating burnout and depression. The analysis confirmed the three-factor structure of the Maslach Burnout Inventory and s multiple factor structure for depression measures. The analysis also provided support for the existence of second-order factors of burnout and depression that accounted for the correlations among the primary factors within each syndrome. The implications of study for the construct validity of burnout and depression are discussed.

The rat probasin gene promoter directs hormonally and developmentally regulated expression of a heterologous gene specifically to the prostate in transgenic mice.

Abstract: An expression cassette carrying 426 basepairs of the rat probasin (PB) gene promoter and 28 basepairs of 5'-untranslated region is sufficient to target the expression of the bacterial chloramphenicol acetyltransferase (CAT) gene specifically to the prostate in transgenic mice. The PB-CAT transgene was expressed in three of five (60%) independent lines of mice, and this expression, as reported previously for the endogenous rat gene, was male specific, restricted primarily to the lateral, dorsal, and ventral lobes of the prostate, with only very low levels of CAT activity detected in the anterior prostate and seminal vesicles. The developmental and hormonal regulation of the transgene also paralleled that reported for the rat gene, with a 70-fold increase in CAT activity in the mouse prostate observed between 2-7 weeks of age, a time corresponding to sexual maturation. PB-CAT activity in the prostate declined after castration to 3.5% of the precastration level, and the CAT activity in castrated males approa...

Prevalence of depression in the terminally ill: effects of diagnostic criteria and symptom threshold judgments

Abstract: Objective Two issues that may influence the diagnosis of depression in the medically ill are 1) the severity with which symptoms must be expressed before they are considered clinically significant and 2) how to deal with somatic symptoms that may be caused by medical illness. This study used different approaches to case identification to examine prevalence rates for major and minor depression in a group of terminally ill cancer patients. Methods Semistructured diagnostic interviews were conducted with 130 patients receiving palliative care. Diagnoses according to the Research Diagnostic Criteria (RDC) were compared with diagnoses according to Endicott's revised criteria (which involve replacing somatic symptoms with non-somatic alternatives) when either a low-severity or a high-severity threshold for classifying RDC criterion A symptoms was used. Results A low-threshold (less stringent) diagnostic approach greatly increased the overall prevalence of major and minor depressive episodes with both the RDC and the Endicott criteria. With high thresholds, the RDC and the Endicott criteria were equivalent, whereas with low thresholds the Endicott substitutions identified fewer cases of major (but not minor) depression. Conclusions Small differences between investigators in the applications of symptom-severity thresholds can result in large differences in prevalence rates for depression. However, the inclusions of somatic symptoms in the diagnostic criteria inflates the rates of diagnosis only when these symptoms are used in conjunction with a low-threshold approach.

Mechanical entrainment of fictive locomotion in the decerebrate cat.

Abstract: 1. We examined the ability of muscular and joint afferents from the hip region to entrain fictive locomotion evoked by stimulation of the mesencephalic locomotor region in the decerebrate cat by me...

Histological findings in early routine biopsies of stable renal allograft recipients.

Abstract: Seventy renal allograft biopsies were done in 31 patients, routinely at 1, 2, and 3 months posttransplant, and as clinically indicated, using an automated biopsy "gun." The histological diagnosis was made according to the Banff schema, which emphasizes tubulitis and vascular inflammation over mononuclear cell infiltration. Fifty-three biopsies satisfied histological inclusion criteria. Twenty-nine biopsies were obtained from stable patients, defined as those in whom serum creatinine had changed < 10% in 2 weeks, and in whom immunosuppression (cyclosporine, azathioprine, and prednisone) had not been increased in that interval. Of these biopsies, 30% (9/29) showed rejection, which could not have been predicted from pretransplant (HLA mismatch, panel-reactive antibody titer) or posttransplant (cyclosporine and serum interleukin 2 receptor levels) variables. The significance of these early subclinical rejection episodes is unknown, and their effects on long-term graft histology and function are being examined in a controlled study.

Hyaluronan and the hyaluronan receptor RHAMM promote focal adhesion turnover and transient tyrosine kinase activity.

Abstract: The molecular mechanisms whereby hyaluronan (HA) stimulates cell motility was investigated in a C-H-ras transformed 10T 1/2 fibroblast cell line (C3). A significant (p < 0.001) stimulation of C3 cell motility with HA (10 ng/ml) was accompanied by an increase in protein tyrosine phosphorylation as detected by anti-phosphotyrosine antibodies using immunoblot analysis and immunofluorescence staining of cells. Tyrosine phosphorylation of several proteins was found to be both rapid and transient with phosphorylation occurring within 1 min of HA addition and dissipating below control levels 10-15 min later. These responses were also elicited by an antibody generated against a peptide sequence within the HA receptor RHAMM. Treatment of cells with tyrosine kinase inhibitors (genistein, 10 micrograms/ml or herbimycin A, 0.5 micrograms/ml) or microinjection of anti-phosphotyrosine antibodies inhibited the transient protein tyrosine phosphorylation in response to HA as well as prevented HA stimulation of cell motility. To determine a link between HA-stimulated tyrosine phosphorylation and the resulting cell locomotion, cytoskeletal reorganization was examined in C3 cells plated on fibronectin and treated with HA or anti-RHAMM antibody. These agents caused a rapid assembly and disassembly of focal adhesions as revealed by immunofluorescent localization of vinculin. The time course with which HA and antibody induced focal adhesion turnover exactly paralleled the induction of transient protein tyrosine phosphorylation. In addition, phosphotyrosine staining colocalized with vinculin within structures in the lamellapodia of these cells. Notably, the focal adhesion kinase, pp125FAK, was rapidly phosphorylated and dephosphorylated after HA stimulation. These results suggest that HA stimulates locomotion via a rapid and transient protein tyrosine kinase signaling event mediated by RHAMM. They also provide a possible molecular basis for focal adhesion turnover, a process that is critical for cell locomotion.

1H MRS of high grade astrocytomas: Mobile lipid accumulation in necrotic tissue

Abstract: Sixty-four samples from six grade 4 astrocytomas were investigated ex vivo by 1H MRS at 360 MHz and subsequently by histopathology to obtain percentages of viable and necrotic tumour and grey and white matter. MR-visible lipids were detected in 87% of tumour samples. Necrotic foci were < 3 x 3 x 6 mm3. The means of the intensities/unit weight tissue of the lipid resonances at 5.33, 2.80, 1.29 and 0.89 ppm were significantly higher (p < 0.05) for three sets of comparisons: samples with 85-100% vs 50-75%; with 50-75% vs 10-40% and with 10-40% vs 0-5% necrosis. For the lipid resonance at 2.04 ppm the difference in the means was significant only for samples with 50-75% compared to those with 85-100% necrosis, because for samples with < 50% necrosis resonances from glutamine and possibly small amounts of glutamate, gamma-aminobutyrate and N-acetylaspartate anions contribute significantly to the spectral area at 2.0 ppm. We conclude that necrotic foci below MRI resolution yield the resonances at 1.3 and 0.9 ppm, and contribute to the intense resonance at 2.0 ppm observed in in vivo 1H spectra of some high grade astrocytomas.

Setting diagnostic thresholds for social phobia: considerations from a community survey of social anxiety

Abstract: Objective: The goal of this study was to gain a broader perspective on social anxiety in the community than has been achieved by epidemiologic surveys to date Method: The authors conducted a telephone survey ofsocial anxiety among 526 randomly selected respondents in a medium-sized Canadian city Results: Sixty-one percent of the respondents reported being much or somewhat more anxious than other people in at least one ofthe seven social situations surveyed Speaking to a large audience (ie, public speaking) was the most frequently feared situation (endorsed by 550% of the respondents), followed by speaking to a small group of familiar people (249%), dealing with people in authority (233 %), attending social gatherings (145%), speaking to strangers or meeting new people (1 3 7%), and eating (7 1 %) or writing (5 1 %) in front of others When the threshold for caseness was systematically modified-by altering the required level ofpsychosocial interference or distress or by including or excluding subjects with pure public speaking phobia-the rate of “social anxiety syndrome “ in the community varied from 19% to 1 8 7%; 7 1 % was the prevalence when the criteria were set to conform with DSM-III-R Conclusions: Social anxiety is common in the community, but precise delineation of the prevalence of “social phobia “ depends heavily on where the diagnostic threshold is set IfDSM-III-R criteria had been applied in previous epidemiologic studies, it is likely that those studies would have documented prevalences ofsocial phobia that are several times as high as the currently accepted rates

Reflecting time-of-flight mass spectrometer with an electrospray ion source and orthogonal extraction.

Abstract: An electrospray source has been coupled to a reflecting time-of-flight mass spectrometer. The ions enter as a continuous beam in a direction perpendicular to the spectrometer axis and are formed into short bursts of ions with velocities parallel to the axis by electrical pulses applied to injection electrodes. The instrument may be operated either in the linear mode, with ions detected behind the electrostatic mirror, or in the reflecting mode, with ions detected after reflection. In the latter case the time resolution is < or = 8 ns for m/z approximately 600, enabling observation of individual isotopic peaks for masses up to about 4000 u. The sensitivity is adequate to enable measurement of mass spectra for 10 fmol of cytochrome c (approximately 12,000 u). The spectrometer does not limit the range of m/z values, and ions have been observed up to m/z approximately 6000. With proper adjustment of pH and other conditions in the source, the ionization is very soft, enabling injection of weakly bound complexes; these have been accelerated and measured in the spectrometer without observable fragmentation.

Glycogen Storage Disease in Adults

Abstract: Objective: To identify complications amenable to prevention in adults with glycogen storage disease (GSD) types Ia, Ib, and III and to determine the effect of the disease on social factors. Design:...

Deoxyribonucleoside triphosphate levels: A critical factor in the maintenance of genetic stability

Abstract: DNA precursor pool imbalances can elicit a variety of genetic effects and modulate the genotoxicity of certain DNA-damaging agents These and other observations indicate that the control of DNA precursor concentrations is essential for the maintenance of genetic stability, and suggest that factors which offset this control may contribute to environmental mutagenesis and carcinogenesis In this article, we review the biochemical and genetic mechanisms responsible for regulating the production and relative amounts of intracellular DNA precursors, describe the many outcomes of perturbations in DNA precursor levels, and discuss implications of such imbalances for sensitivity to DNA-damaging agents, population monitoring, and human diseases