Identification of amino acid residues responsible for the alpha5 subunit binding selectivity of L-655,708, a benzodiazepine binding site ligand at the GABA(A) receptor

L-655,708 is a ligand for the benzodiazepine site of the gamma-aminobutyric acid type A (GABA(A)) receptor that exhibits a 100-fold higher affinity for alpha5-containing receptors compared with alpha1-containing receptors. Molecular biology approaches have been used to determine which residues in the alpha5 subunit are responsible for this selectivity. Two amino acids have been identified, alpha5Thr208 and alpha5Ile215, each of which individually confer approximately 10-fold binding selectivity for the ligand and which together account for the 100-fold higher affinity of this ligand at alpha5-containing receptors. L-655,708 is a partial inverse agonist at the GABA(A) receptor which exhibited no functional selectivity between alpha1- and alpha5-containing receptors and showed no change in efficacy at receptors containing alpha1 subunits where amino acids at both of the sites had been altered to their alpha5 counterparts (alpha1Ser205-Thr,Val212-Ile). In addition to determining the binding selectivity of L-655,708, these amino acid residues also influence the binding affinities of a number of other benzodiazepine (BZ) site ligands. They are thus important elements of the BZ site of the GABA(A) receptor, and further delineate a region just N-terminal to the first transmembrane domain of the receptor alpha subunit that contributes to this binding site.

Comparison of two calcium blockers on hemodynamics, left ventricular mass, and coronary vasodilatory in advanced hypertension

Dihydropyridine and nondihydropyridine calcium channel blockers (CCB) differ in pharmacologic characteristics. Few clinical studies distinguish effects of CCB as monotherapy. We conducted a comprehensive comparison of two CCB on patients with moderate to severe hypertension. Thirty patients with pretreatment diastolic blood pressures > or = 100 mm Hg were randomly assigned to either nifedipine-GITS or verapamil-SR. Dose titration achieved a diastolic blood pressure of < or = 95 mm Hg or a decrease of > or = 15 mm Hg over 4 weeks. Clinic blood pressure (BP), 24-h ambulatory BP, exercise BP, left ventricular mass, systolic and diastolic function by echocardiography, and coronary flow reserve by split-dose thallium-201 imaging with adenosine were assessed at baseline, end of titration, 3 months and 6 months of treatment. Plasma renin activity, atrial natriuretic peptide, norepinephrine, and epinephrine were assayed. Both drugs caused similar reductions in clinic and 24-h ambulatory BP and similar reductions in left ventricular mass index. Compared to nifedipine-GITS, verapamil-SR produced a significantly lower resting and peak exercise heart rate. Nifedipine-GITS elicited a lower peak exercise systolic BP. At end titration nifedipine-GITS produced lower plasma atrial natriuretic peptide levels, no longer apparent by 6 months. Plasma norepinephrine was lower with verapamil-SR, also at end titration and at 3 months, but not at 6 months. Plasma epinephrine and plasma renin activity were unchanged by either drug. There was no difference for systolic or diastolic left ventricular function or coronary flow reserve between the two treatments. Once daily nifedipine-GITS and verapamil-SR are equally effective for reduction of arterial pressure in moderate to severe hypertension. Differences in their hemodynamic profiles and neurohormonal responses are consistent with preclinical pharmacologic characteristics. The clinical implications of their similarities and differences remain to be fully evaluated in outcome studies.

Palliative care nurses' perceptions of good and bad deaths and care expectations: a qualitative analysis

Individuals who are involved with the death of a person with a terminal illness will often classify the death as either 'good' or 'bad'. Families and healthcare practitioners assess many factors when determining their 'success' or 'failure' in assisting someone in the terminal phase. Palliative care nurses are particularly vulnerable to self-assessments about care of the dying, because death is a daily occurrence. Feelings of failure, unmet expectations and feeling of regret about not being able to prevent a traumatic death may be a source of stress for palliative care nurse and may affect their abilities to function effectively. This article reports the findings of a study involving interviews with 20 palliative care nurses to determine their perceptions of a good and bad death. The study also examined the expectations they hold of themselves and that they believe others hold of them in helping patients to attain a good death. Clinical implications are discussed based on these findings.

Concurrent consultations with physicians and providers of alternative care: results from a population-based study

OBJECTIVE

We examined the factors related to consultations with both physicians and alternative practitioners, compared with visits to physicians only.

METHODS

A telephone survey (random-digit dialling) collected information from 818 adults living in and around Saskatoon. Respondents reported consultations with alternative practitioners and physicians in the previous 12 months.

RESULTS

Approximately one in five respondents had consulted both a physician and an alternative practitioner. Among respondents under 65 years of age, having one or more chronic medical conditions significantly increased the likelihood of concurrent use of care. Men, individuals suffering from back pain or migraines, those reporting an elevation level of distress, and those for whom spiritual values were important were also more likely to use both types of care.

INTERPRETATION

Consultations with alternative care providers occur as an adjunct to, rather than a replacement of visits to physicians. Particular types of medical conditions as well as psychosocial and spiritual factors are determinants of concurrent use of physicians and alternative practitioners.

Effect of vaccination on experimental infection with Bordetella bronchiseptica in dogs

OBJECTIVE

To determine comparative efficacy of vaccines administered IM and intranasally, used alone or sequentially, to protect puppies from infection with Bordetella bronchiseptica and determine whether systemic or mucosal antibody response correlated with protection.

DESIGN

Randomized controlled trial.

ANIMALS

50 specific-pathogen-free Beagle puppies.

PROCEDURE

In 2 replicates of 25 dogs each, 14-week-old puppies that were vaccinated against canine distemper virus and parvovirus were vaccinated against B bronchiseptica via intranasal, IM, intranasal-IM, or IM-intranasal administration or were unvaccinated controls. Puppies were challenge exposed via aerosol administration of B bronchiseptica 2 weeks after final vaccination. Clinical variables and systemic and mucosal antibody responses were monitored for 10 days after challenge exposure. Puppies in replicate 1 were necropsied for histologic and immunohistochemical studies.

RESULTS

Control puppies that were seronegative before challenge exposure developed paroxysmal coughing, signs of depression, anorexia, and fever. Vaccinated puppies (either vaccine) that were seronegative before challenge exposure had fewer clinical signs. Puppies that received both vaccines had the least severe clinical signs and fewest lesions in the respiratory tract. Vaccinated dogs had significantly higher concentrations of B bronchiseptica-reactive antibodies in serum saliva before and after challenge. Antibody concentrations were negatively correlated with bacterial growth in nasal cavity and pharyngeal samples after challenge exposure.

CONCLUSIONS AND CLINICAL RELEVANCE

Parenterally and intranasally administered vaccines containing B bronchiseptica may provide substantial protection from clinical signs of respiratory tract disease associated with infection by this bacterium. Administration of both types of vaccines in sequence afforded the greatest degree of protection against disease.

Measurement of the speed of sound in ethanol/water mixtures

Ethanol/water mixtures are used commonly as a propagation medium in test objects to calibrate the measurement facilities of ultrasound (US) imaging systems. The speed of sound c in the mixture should be known, preferably with an accuracy of +/-0.1% where clinical measurements to +/-1% are required. This article describes measurements of c in several ethanol/water mixtures over a range of temperatures using a simple pulse superposition technique, which gives an estimated measurement uncertainty of 0.1%. The measurements show that, at 20 degrees C, a mixture of 9.5 +/- 0.25% ethanol by volume in distilled water is required to give a speed of 1540 +/- 1.5 m s(-1). However, to achieve this accuracy, the temperature of the mixture must be maintained in the range 20 degrees +/- 0.75 degrees C.

Delta 32 mutation of the chemokine-receptor 5 gene in inflammatory bowel disease

The gene encoding chemokine receptor 5 (CCR5) is colocalized to the microsatellite marker D3S1573, which was linked with inflammatory bowel disease. Genetic heterogeneity in inflammatory bowel disease might be defined by a combination of the p-ANCA status and immunoregulatory genes. One hundred and twenty healthy unrelated controls, 101 patients with Crohn's disease, and 99 patients with ulcerative colitis were genotyped for the Delta 32 mutation of the CCR5 gene. The presence of p-ANCA was determined by the use of indirect immunofluorescence. After genotyping, patients were stratified according to p-ANCA status. The frequency of the Delta 32 mutation was not significantly different in controls and patients with Crohn's disease or ulcerative colitis (P 0.207 or more). Moreover, the frequency of the mutation was not significantly different in patients with inflammatory bowel disease after stratification for the p-ANCA status (P 0.482). Regardless of the p-ANCA status, Crohn's disease and ulcerative colitis are not associated with the Delta 32 mutation of the CCR5 gene.

Women's initiative for nonsmoking (WINS) II: the intervention

Women's Initiative for Nonsmoking (WINS) is a randomized clinical trial designed to test the efficacy of a nurse-managed smoking cessation and relapse prevention intervention designed specifically for women. The WINS intervention is rooted in social learning theory, specifically that of self-efficacy. It is a multimedia approach that provides education, counseling, and telephone follow-up that meet the smoking cessation intervention guidelines established by the Agency for Health Care Policy and Research. The WINS intervention has been successfully implemented in more than 140 women and has proven to be feasible and well accepted by both the women and their health care providers. Although the intervention in the protocol-driven randomized clinical trial was begun in the hospital, it is anticipated that nurses in any setting, inpatient or outpatient, who serve populations at risk for cardiovascular disease, peripheral vascular disease, lung cancer, or pulmonary disease could successfully provide the intervention.

A client-centered model: discharge planning in Juvenile Justice Centres in New South Wales, Australia

Health care delivered in Juvenile Justice Centres in New South Wales, Australia, leads to improvement in the health status of detainees while in custody but this declines on discharge and is contributed to by a breakdown in continuity of care. In an effort to halt this decline in health status, a model of interdisciplinary discharge planning is proposed to address the interface between Juvenile Justice Centres and adult correctional facilities and the community. Key features of the process are: collaboration through the development of links by establishment of a community liaison co-ordinator position; open and continuous communication between service providers; continuous involvement of detainees and their significant others; and ongoing support to detainees once discharged. Evaluation of the discharge-planning process ensures that the process is appropriate to meet the needs of this specific and diverse population of young people and supplies feedback to all service providers. The trusting relationship that is developed between detainees and registered nurses within centres leaves nurses ideally placed to co-ordinate the discharge-planning process.

Pharmacology of recombinant human GABA(A) receptor subtypes measured using a novel pH-based high-throughput functional efficacy assay

To facilitate the discovery of novel compounds that modulate human GABA(A) receptor function, we have developed a high throughput functional assay using a fluorescence imaging system. L(tk-) cells expressing combinations of human GABA(A) receptor subunits were incubated with the pH-sensitive dye 2',7'bis-(2-carboxyethyl)-5-(and 6)-carboxyfluorescein, then washed and placed in a 96-well real-time fluorescence plate reader. In buffer adjusted to pH 6.9 there was a robust and persisting acidification response to addition of GABA, which was antagonised by the GABA(A) receptor antagonist bicuculline. The concentration-response relationship for GABA was modulated by allosteric ligands, including benzodiazepine (BZ) site agonists and inverse agonists. The effects of BZ site ligands on the pH response to GABA for receptors containing alpha1beta3gamma2, alpha3beta3gamma2 or alpha5beta3gamma2 subunits were well correlated with results from electrophysiological studies on the same receptor subunit combinations expressed in Xenopus oocytes. Most modulatory compounds tested were found to be relatively unselective across the three subunit combinations tested; however, some showed subtype-dependent efficacy, such as diazepam, which had highest agonist effects on the alpha3beta3gamma2 subtype, substantial but lesser agonism on alpha1beta3gamma2 and still substantial but the least agonism on alpha5beta3gamma2. This indicates that the alpha subunit within the recombinant receptor expressed in L(tk-) cells can affect the efficacy of the response to some BZ compounds. Inhibitors of Na(+)/Cl(-) cotransport, anion/anion exchange and the gastric type of H(+)/K(+) ATPase potently inhibited GABA-evoked acidification, indicating that multiple transporters are involved in the GABA-evoked pH change. This novel fluorescence-based high throughput functional assay allows the rapid characterization of allosteric ligands acting on human GABA(A) receptors.

Mechanisms of population differentiation in marbled murrelets: historical versus contemporary processes

Mechanisms of population differentiation in highly vagile species such as seabirds are poorly understood. Previous studies of marbled murrelets (Brachyramphus marmoratus; Charadriiformes: Alcidae) found significant population genetic structure, but could not determine whether this structure is due to historical vicariance (e.g., due to Pleistocene glaciers), isolation by distance, drift or selection in peripheral populations, or nesting habitat selection. To discriminate among these possibilities, we analyzed sequence variation in nine nuclear introns from 120 marbled murrelets sampled from British Columbia to the western Aleutian Islands. Mismatch distributions indicated that murrelets underwent at least one population expansion during the Pleistocene and probably are not in genetic equilibrium. Maximum-likelihood analysis of allele frequencies suggested that murrelets from "mainland" sites (from the Alaskan Peninsula east) are genetically different from those in the Aleutians and that these two lineages diverged prior to the last glaciation. Analyses of molecular variance, as well as estimates of gene flow derived using coalescent theory, indicate that population genetic structure is best explained by peripheral isolation of murrelets in the Aleutian Islands, rather than by selection associated with different nesting habitats. No isolation-by-distance effects could be detected. Our results are consistent with a rapid expansion of murrelets from a single refugium during the early-mid Pleistocene, subsequent isolation and divergence in two or more refugia during the final Pleistocene glacial advance, and secondary contact following retreat of the ice sheets. Population genetic structure now appears to be maintained by distance effects combined with small populations and a highly fragmented habitat in the Aleutian Islands.

Integration of modeling and acoustic microscopy measurements for thin films

A model for measuring the V(z) curve by line-focus acoustic microscopy contains the reflectance function of the specimen as a principal component. In this paper the reflectance function has been analyzed for multilayered thin films on a substrate for both fast-on-slow and slow-on-fast systems. The phase velocities of modes of surface acoustic wave propagation and their associated mode reflection coefficients can be obtained from the reflectance function. This information can be used together with estimates of the elastic constants to determine suitable frequency ranges for measuring the V(z) curve. Minimization of the difference between phase velocities obtained from measured and calculated V(z) curves is used to determine the elastic constants. Results are presented for TiN films on M2 high-speed steel substrates.

[Effects of cognitive aging on memory performances]

PSYCHOLOGY OF AGING: This article sums up studies on influence of normal aging in memory. Aging is a process involving many dimensions: Psychological, Biological and Social. These elements interact with each other and needed to be considered in the description of human memory aging. COGNITIVE APPROACH OF HUMAN MEMORY: Moreover, researches on human memory have been conducted within the framework of current theoretical views of memory. The present review provides an outline of the cognitive neuropsychology models of memory, its nature, components and organization. CLINICAL APPROACH OF AGING AND MEMORY, CONSEQUENCES: This introduction may help the reader to understand more clearly empirical evidence of age-related differences in memory and attentional functioning. In closing, the human factors psychologists must be take in account while adopting a global approach of the understanding of memory aging. Psychological field provides a complete structure for assessing human being and is helpful before to conclude between normal or pathological memory aging.

[Minimally invasive adrenalectomy with posterior retroperitoneoscopy]

Authors report a total of 14 adrenalectomies performed from a posterior (lumbotomy) approach, using minimally invasive retroperitoneoscopic technique. The "UltraCision" scalpel, an ultrasound activated cutter-coagulation device has been used for operative tissue dissection. Two cases were converted. The mean operating time of the successful 12 cases were 128 minutes. No mortality and no septic complication occurred. The mean operative blood loss of the 12 procedures were less than 100 ml. The mean hospitalisation was 3-5 days, and the complete recovery needed 2-3 weeks. On the basis of our own experiences and the ones of prospective, randomized clinical studies of the literature, the retroperitoneoscopic adrenalectomy from a posterior approach is recommended for the surgical treatment of benign tumours of the suprarenal gland with a size less than 5 cm diameter. The low conversion- and complication-rate, the minimal operative blood loss, the short hospitalization and quick recovery time all are the advantages of this method. It can be performed after previous abdominal operation and in cases with morbid obesity. The technique is suitable for bilateral adrenalectomies as well. This method is not justified for the removal of malignant and/or larger than 5 cm adrenal tumours. Coagulopathies are contraindications.

Tumour necrosis factor alpha and its soluble receptors in juvenile chronic arthritis

OBJECTIVE

To identify possible imbalance of tumour necrosis factor alpha (TNFalpha) and its soluble receptors in the different subgroups of juvenile chronic arthritis (JCA).

METHODS

Serum and synovial fluid samples from 45 children were examined, 25 pauciarticular JCA, 13 polyarticular JCA and seven spondyloarthropathy. TNFalpha, sTNFRI and sTNFRII levels were measured by EASIA and enzyme-linked immunosorbent assay (ELISA). Analysis of the results was carried out using non-parametric tests: Kruskal-Wallis one-way analysis of variance was used to compare the three clinical subgroups; the Mann-Whitney U-test was used to compare group medians.

RESULTS

Thirty-three serum samples were assayed for TNFalpha. There was no significant difference between the three groups using the Kruskal-Wallis analysis of variance. Analysis of synovial fluid TNF levels showed significantly lower levels in the spondyloarthropathy group compared with the pauciarticular JCA (P = 0.01) and the polyarticular group (P = 0.002). Significantly higher levels of sTNFRI were observed in the synovial fluid of the polyarticular JCA group compared with the pauciarticular JCA group (P = 0.004) and similarly for sTNFRII (P = 0.03). Molar ratios were calculated for TNF vs sTNFRI. The sTNFRI/TNFalpha ratio was significantly higher in the spondyloarthropathy group compared with the pauci- (P 0.003) and the polyarticular JCA subgroups (P = 0.003). The combined soluble receptor levels expressed as molar ratio to TNF again showed a significantly higher ratio in the spondyloarthropathy group compared with the pauciarticular group (P = 0.01) and compared with the polyarticular group (P = 0.05).

CONCLUSION

These results suggest that the increased joint destruction observed in polyarticular disease compared with the other two subtypes may be related to the lower sTNFR/TNFalpha ratios observed.

Knowledge-based segmentation of thoracic computed tomography images for assessment of split lung function

The assessment of differential left and right lung function is important for patients under consideration for lung resection procedures such as single lung transplantation. We developed an automated, knowledge-based segmentation algorithm for purposes of deriving functional information from dynamic computed tomography (CT) image data. Median lung attenuation (HU) and area measurements were automatically calculated for each lung from thoracic CT images acquired during a forced expiratory maneuver as indicators of the amount and rate of airflow. The accuracy of these derived measures from fully automated segmentation was validated against those from segmentation using manual editing by an expert observer. A total of 1313 axial images were analyzed from 49 patients. The images were segmented using our knowledge-based system that identifies the chest wall, mediastinum, trachea, large airways and lung parenchyma on CT images. The key components of the system are an anatomical model, an inference engine and image processing routines, and segmentation involves matching objects extracted from the image to anatomical objects described in the model. The segmentation results from all images were inspected by the expert observer. Manual editing was required to correct 183 (13.94%) of the images, and the sensitivity, specificity, and accuracy of the knowledge-based segmentation were greater than 98.55% in classifying pixels as lung or nonlung. There was no significant difference between median lung attenuation or area values from automated and edited segmentations (p > 0.70). Using the knowledge-based segmentation method we can automatically derive indirect quantitative measures of single lung function that cannot be obtained using conventional pulmonary function tests.

Neurodevelopmental profile of a new dysmorphic syndrome associated with submicroscopic partial deletion of 1p36.3

We describe four children with dysmorphic syndrome with severe learning disability (SLD). Their chromosomes had been normal on conventional cytogenetic examination. However, screening using a multiprobe fluorescence in situ hybridisation (FISH) technique for subtelomeric abnormalities revealed a deletion of the p arm of chromosome 1. The physical features include body asymmetry, microcephaly, distinctive facies with deep-set eyes, sharply defined eye sockets, and mid-face hypoplasia; the neurodevelopmental profile was characterised by SLD, motor delay with hypotonia, markedly delayed visual maturation, and postural asymmetry together with epilepsy. This phenotype is consistent with that described for partial monosomy for 1p36.3.

Contraceptive use in Canada: 1984-1995

CONTEXT

In every country, contraceptive behavior has important implications for fertility and the prevalence of sexually transmitted diseases (STDs). There has been relatively little attention to contraceptive practices in Canada, however, particularly how patterns of method use may have changed.

METHODS

Data on contraceptive use were collected from 5,315 women in the 1984 Canadian Fertility Survey, and from 3,220 women and 3,449 men in the 1995 General Social Survey.

RESULTS

Among Canadian women aged 15-49, current contraceptive use declined from 69% to 60% between 1984 and 1995. Pill use dropped from 19% to 17%, and IUD use declined from 6% to 3%. However, during the same period, condom use increased from 6% to 10%; tubal ligation declined from 24% to 17%, while vasectomy increased. In addition, the proportion of women sterilized for reasons other than contraception rose between 1984 and 1995. Men were less likely to rely on sterilization than were women (31 % vs. 40%). Men reported higher levels of condom use (22%), but lower levels of pill use among their partners (9%), than did women (10% and 17%, respectively).

CONCLUSIONS

Contraceptive behavior in Canada is unique: The decline in contraceptive use over the last decade has left Canada's overall contraceptive prevalence among the lowest in the industrialized world, and the rate of sterilization among the highest These changes in contraceptive behavior complicate efforts to plan for social and health needs, particularly policy decisions focusing on reducing infections with STDs.