Expression of the recombinant anchorless N-terminal domain of mouse hepatitis virus (MHV) receptor makes hamster of human cells susceptible to MHV infection

Mouse hepatitis virus (MHV) receptor, the receptor for the murine coronavirus MHV, was expressed in MHV-resistant hamster and human cells as a series of mutant, recombinant glycoproteins with carboxy-terminal deletions lacking the cytoplasmic tail, transmembrane domain, and various amounts of the immunoglobulin constant-region-like domains. The soluble receptor glycoproteins containing the N-terminal virus-binding domain were released into the supernatant medium and inactivated the infectivity of MHV-A59 virions in a concentration-dependent manner. Surprisingly, some of the anchorless glycoproteins were found on the plasma membranes of transfected cells by flow cytometry, and these cells were rendered susceptible to infection with three strains of MHV. Thus, in the cells in which the anchorless, recombinant receptor glycoprotein is synthesized, some of the protein is bound to an unidentified moiety on the plasma membrane, which allows it to serve as a functional virus receptor.     

Doing the right thing at the right time? The interaction of stages and processes of change in successful smoking cessation

Research on the transtheoretical model has provided substantial support for both stages of change and processes of change (coping strategies influencing successful behavior change). This study examined whether timing of process use (using particular change processes during one stage and not during others) influences quit success. Hypothesized patterns of optimal process use were those marked by more use of experiential processes and less use of behavioral processes during contemplation and preparation and by the reverse pattern during action. Participants (N = 388) began in contemplation or preparation and took action during a 4-6 week period. Multivariate analyses of covariance examined the relationship between patterns of process use and success in staying quit both at 1-month follow-up and 5-6 months later. For the most part, results supported the hypothesis that successful stage transitions involve doing the right thing at the right time: engaging in experiential process activities during contemplation and preparation stages and shifting to behavioral process activities during action.     

Hypertrophic myocardiopathy with isoelectric T waves

INTRODUCTION AND OBJECTIVES: The lack of specificity of electrocardiographic (ECG) recording showing isoelectric T-waves often leads to diagnostic doubts. This study attempts to demonstrate that asymptomatic patients who demonstrate benign forms of hypertrophic cardiomyopathy may be identified from a typical ECG pattern showing isoelectric T-waves. METHODS: In 45 out of 5,126 asymptomatic healthy aircrew members, an ECG pattern which showed isoelectric T-waves in all leads, but were normal in V2 and V3, was found. 12 of them had negative T-waves in III and aVF leads. Cardiac echo-Doppler, Bruce test and 24-hour Holter recordings were performed in 29 of the 45 cases; all were males aged 30-55 (43.1 +/- 7.1) without any associated disorder nor engaged in heavy exercise, and a control group of 15 healthy subjects. In each of the 29 cases, 2-21 ECG's (11.1 +/- 6.3) performed over a period of 2 to 20 years (13.0 +/- 5.9) were reviewed. RESULTS: In 23 of the 29 cases (79.3%), echo-Doppler criteria of non obstructive mild hypertrophic cardiomyopathy were found. T-waves became normal during exercise testing, returning to isoelectric during recovery, in 19 of the 23 cases. In 17 of these cases, reversible T-wave changes were observed between successive ECG's; T-wave changes became clearly negative when the level of exercise was increased. Holter recordings did not show pathological findings. CONCLUSIONS: We believe that echo-Doppler studies must be performed in asymptomatic patients showing the ECG pattern described above, because they are strongly suspicious of having mild hypertrophic cardiomyopathy.     

Biocompatibility of posterior restorative materials

Biocompatibility of dental materials is an important consideration for the patient, clinician, laboratory technician and manufacturer. This paper examines biocompatibility testing methods and the biocompatibility of posterior restorative materials, including amalgam, casting alloys, resin composites, dentin bonding agents, cements, porcelains and ceramics.     

Age-related changes in the electrophysiological response to visual stimulus novelty: a topographical approach

The relationship of task relevance and stimulus probability to P300 morphology, latency and distribution was assessed. Eight year olds and adults completed visual oddball tasks of recognition memory with frequent non-target (60%), infrequent target (20%), and infrequent novel (20%) stimuli. Stimuli consisted of 2 female faces posing neutral expressions, and 40 trial unique novel photographs depicting scenes, animals, objects or abstract patterns. Event-related potentials were recorded from 17 electrodes over frontal, central and parietal scalp, including lateral temporal sites. All stimuli elicited P300 responses at parietal electrodes, with the largest responses to the target stimuli (relevant and infrequent). The P300 responses of adults and children were morphologically dissimilar, with children showing broader peaks and latency shifts across electrodes. In addition, the eight year olds displayed a frontal negativity to novel stimuli which was absent in the responses of adult participants. Results suggest that different anatomical or functional circuitry may be involved in the processing of novelty for adults as compared to eight year olds.