Biomedical subjects

J E Joseph

Publications and source records attributed to J E Joseph.

7 recordsLinked to original sources

PubMed2000

Effect of sex and joystick experience on pursuit tracking in adults.

Using a joystick, adults (n = 39 males, 40 females in Experiment 1; n = 35 males, 40 females in Experiment 2; and n = 18 males, 18 females in Experiment 3) performed a computerized pursuit tracking task. Contrary to previously reported findings, the males were not more accurate than the females when performance was adjusted for prior perceptual-motor experience. Although no sex differences were found in a speeded tracking task, in an inverted tracking task the males exhibited a significant performance advantage; that advantage remained after several blocks of practice. Because participants' performance was adjusted statistically for prior perceptual-motor experience, the male advantage in inverted tracking was not related to experience. Rather, more proficient inverted tracking performance was associated with higher 3-dimensional mental rotations scores. In sum, sex differences in normal pursuit tracking may be better explained by differences in perceptual-motor experience. Inverted tracking, however, may depend on proficiency with spatial transformations.

Computers↗

PubMed1999

Utilizing hemodynamic delay and dispersion to detect fMRI signal change without auditory interference: the behavior interleaved gradients technique.

A major problem associated with the use of functional magnetic resonance imaging (fMRI) is the attendant gradient noise, which causes undesirable auditory system stimulation. A method is presented here that delays data acquisition to a period immediately after task completion, utilizing the physiological delay and dispersion between neuronal activity and its resulting hemodynamic lag. Subjects performed finger movements with the gradients off, followed by a rest period with the gradients on. This resulted in task-related signals comparable to those obtained with concurrent task performance and image data acquisition. This behavior interleaved gradients technique may be particularly useful for the studies involving auditory stimulation or overt verbal responses.

Acoustic Stimulation↗

PubMed1998

Platelet activation markers and the primary antiphospholipid syndrome (PAPS).

Platelets play an important part in normal haemostasis, and are likely to be involved in the thromboembolism seen in the primary antiphospholipid syndrome (PAPS). Evidence exists for platelet activation in this disorder, and new flow cytometric techniques have made it possible to detect low levels of activation. We have previously studied the expression of the platelet activation markers CD62p and CD63, percentage of reticulated platelets, and levels of soluble P-selectin in a group of PAPS patients. Median platelet CD63 expression and plasma soluble P-selectin levels were significantly increased in PAPS patients compared to a group of controls; there was no difference in reticulated platelet percentages between the two groups. Additional assays of platelet activation (PAC-1 expression, Annexin V binding, platelet microparticles and complexes) are being developed and assessed with respect to disease activity, thrombosis risk and effects of antithrombotic therapy.

Annexin A5↗

PubMed1998

Platelet activation and turnover in the primary antiphospholipid syndrome.

Thromboembolism is a common occurrence in patients with the antiphospholipid syndrome (APS). The mechanism responsible for this phenomenon is unclear; there are several theories. One possibility is that a pathogenic interaction exists between antiphospholipid antibodies and platelets, leading to their activation. This study examined the expression of the platelet activation markers CD62 and CD63 by flow cytometry in 20 patients with the primary antiphospholipid syndrome (PAPS). Levels of soluble P-selectin were also assayed. Reticulated platelets were measured as an indicator of increased platelet production and/or turnover. Median CD63 expression was significantly increased in patients (14.3%) compared to a group of healthy controls (10.1%, P = 0.0008). There was no significant difference in median CD62 expression or percent reticulated platelets between the two groups. The median level of soluble P-selectin was significantly higher in PAPS patients (35.5 ng/ml) compared to controls (18.8 ng/ml, P = 0.0028). Patients receiving aspirin had lower median CD63 values (13.1%) when compared to those patients who were not (18.0%, P = 0.023). However, aspirin therapy did not prevent significant platelet activation occurring in some individual patients. Our data suggest that although not excessive, there is a degree of increased platelet activation in some PAPS patients, which is not always suppressed by antiplatelet therapy with aspirin.

Adult↗

PubMed1997

Color processing in object verification.

This study examined the effect of different object verification tasks on perceptual and conceptual color processing. Participants decided whether two successively presented stimuli (two pictures or a word then a picture) referred to the same object. Although the task did not require object-color processing, prototypical object-color was semantically activated and influenced verification decisions. This automatic conceptual color processing was more powerful than perceptual processing of the surface color presented in the picture. Moreover, conceptual color processing occurred in tasks involving only two pictures, implying that activation of prototypical color does not depend on verbal processing. Rather, activation of prototypical color depends on whether pictures are semantically encoded during verification, which in turn, occurs when verification cannot proceed from structural object information.

Cognition↗

PubMed1997

New antiplatelet drugs.

Antiplatelet drugs are used in a wide range of disorders, either as sole agents or as adjuncts to other therapies. Aspirin has been shown to be clinically effective in a number of ischaemic conditions and has been in use for many years. The newer agents, ticlopidine and clopidogrel (which are thought to inhibit ADP-mediated platelet reactions) are also effective and may prove to be superior to aspirin in certain indications. However, ticlopidine in particular has a different spectrum of side-effects, which may eventually limit its widespread use. The Gp IIb/IIIa antagonists have been most extensively investigated in the acute coronary syndromes, and shown to significantly improve outcome. Most of these studies have utilized agents which need to be given parenterally, and subsequently oral compounds are currently being developed. A number of other antiplatelet drugs such as prostacyclin and its analogues, as well as thromboxane inhibitors have been studied over the years, but overall they have failed to demonstrate any real clinical advantage.

Blood Platelets↗

PubMed1996

Semantic versus perceptual influences of color in object recognition.

The influence of color as a surface feature versus its influence as stored knowledge in object recognition was assessed. Participants decided whether a briefly presented and masked picture matched a test name. For pictures and words referring to similarly shaped objects, semantic color similarity (SCS) was present when picture and word shared the same prototypical color (e.g., purple apple followed by cherry). Perceptual color similarity (PCS) was present when the surface color of the picture matched the prototypical color of the named object (e.g., purple apple followed by blueberry). Response interference was primarily due to SCS, despite the fact that participants based similarity ratings on PCS. When uncolored objects were used, SCS interference still occurred, implying that the influence of SCS did not depend on the presence of surface color. The results indicate that, relative to surface color, stored color knowledge was more influential in object recognition.

Adult↗