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J Malik

Publications and source records attributed to J Malik.

12 recordsLinked to original sources
PubMed1997

Association of the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index with measures of disease activity and health status in patients with systemic lupus erythematosus.

OBJECTIVE: To examine the internal consistency and validity of the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) with respect to disease activity, health status, and medication score. METHODS: A prospective cross sectional study of patients with systemic lupus erythematosus (SLE) attending a specialist lupus outpatient clinic between July 1994 and February 1995. The internal consistency of the SDI components was examined using Cronbach's coefficient alpha. The associations of the SDI components with disease activity measured by the British Isles Lupus Assessment Group (BILAG) index, health status measured by the Medical Outcomes Study (MOS) Short Form 20, and with a medication score were analyzed using Spearman's rank correlation coefficient (p). RESULTS: 133 women and 8 men ranging in age from 20.1 to 88.7 years (mean 41.1, SD 12.5) were studied. With few exceptions, the components of the SDI that reflect damage in different organ systems were not associated with each other. We found a significant although weak relationship between some related SDI and BILAG components (p 0.25 to 0.28; p < 0.01). While damage to the musculoskeletal system was associated with limitations in physical functioning measured with the MOS Short Form 20 (p-0.30; p < 0.01) and renal damage inversely with fatigue (p-0.23; p < 0.01) there was no significant relationship of other SDI components with the MOS Short Form 20. Renal and neuropsychiatric damage were associated significantly with the medication score (p 0.27 and 0.23; p < 0.01). CONCLUSION: The components of the SDI are valid in that they are associated with disease activity in the respective organ systems and some of them with a medication score. However, damage in different organ systems in SLE does not follow a common pattern. It is thus suggested that the SDI profile be used in addition to the SDI total score as an endpoint in clinical and epidemiological studies.

Adult↗
PubMed1996

Further validation of the BILAG disease activity index in patients with systemic lupus erythematosus.

OBJECTIVE: To examine the association among the BILAG disease activity index components and their relations with global assessments, health status, and laboratory tests with regard to the validity of the BILAG index. METHODS: A cross sectional study of consecutive patients with systemic lupus erythematosus (SLE) attending a specialist lupus outpatient clinic between July 1994 and February 1995. The internal consistency of the British Isles Lupus Assessment Group (BILAG) index-a disease activity assessment system for SLE patients, based on the principle of the physician's intention to treat-was examined using Cronbach's coefficient alpha. The association of the components of the BILAG index with health status as measured with the MOS Short Form 20 (SF-20), with patients' and doctors' global assessments of patient wellbeing and with laboratory tests was analysed with Spearman rank correlations. RESULTS: 133 female and eight male patients, age 20.1 to 88.7 years (mean 41.1, SD 12.5), were included. With few exceptions, the components of the BILAG index which reflect disease activity in different organ systems were not associated with each other. With the exception of the mucocutaneous component, we found a significant relation between all components of BILAG and global assessment of patient wellbeing, health status, erythrocyte sedimentation rate, or serum C3 level. CONCLUSIONS: The study confirms the validity of all but the mucocutaneous component of the BILAG index. However, disease activity in different organ systems in SLE does not follow a common pattern. Thus the individual BILAG components should be used rather than the total BILAG score as a primary endpoint in clinical and epidemiological studies. To capture the total effect of SLE on an individual measures of disease activity, damage, and health status are all needed.

Adult↗
PubMed1994

A computational model for shape from texture.

Shape from texture is best analysed in a two-stage framework analogous to stereopsis and structure from motion: (a) computing the 'texture distortion' from the image; and (b) interpreting the 'texture distortion' to infer the orientation and shape of the scene surface in 3D. We model the texture distortion at a point in any particular direction on the image plane as an affine transformation and derive the relationship between the parameters of the affine transformation and the surface shape and orientation. We have developed a technique for estimating affine transforms between nearby image patches which is based on solving a system of linear constraints derived from a differential analysis. It is not necessary explicitly to identify texels or make restrictive assumptions about the nature of the image texture like isotropy. We have developed two different models for recovering surface orientation (slant and tilt) and shape (principal curvatures and directions) based on the estimated affine transforms in a number of directions. Experimental results are presented on images of planar and curved surfaces under perspective projection.

Animals↗
PubMed1990

Preattentive texture discrimination with early vision mechanisms.

We present a model of human preattentive texture perception. This model consists of three stages: (1) convolution of the image with a bank of even-symmetric linear filters followed by half-wave rectification to give a set of responses modeling outputs of V1 simple cells, (2) inhibition, localized in space, within and among the neural-response profiles that results in the suppression of weak responses when there are strong responses at the same or nearby locations, and (3) texture-boundary detection by using wide odd-symmetric mechanisms. Our model can predict the salience of texture boundaries in any arbitrary gray-scale image. A computer implementation of this model has been tested on many of the classic stimuli from psychophysical literature. Quantitative predictions of the degree of discriminability of different texture pairs match well with experimental measurements of discriminability in human observers.

Algorithms↗
PubMed1989

The herbicide glyphosate.

Glyphosate has broad spectrum herbicidal activity against a wide range of annual and perennial weeds. The environmental properties of this herbicide such as its soil immobility, rapid soil inactivation and soil biodegradation are outstanding. This herbicide is practically non-toxic to non-plant life forms such as aquatic and avian species, animals and man. Metabolism studies with pure bacterial cultures indicate that glyphosate is metabolized to either aminomethylphosphonate and glyoxylate or sarcosine and phosphate in most bacteria. The enzyme C-P lyase, which catalyzes the cleavage of the carbon-phosphorus bond of phosphonates including glyphosate, appears to be complex, containing multiple subunits. Mode of action studies have demonstrated that glyphosate kills plants by inhibiting the enzyme 5-enolpyruvylshikimate-3-phosphate synthase, involved in the biosynthesis of aromatic compounds. The status of our understanding of these aspects of glyphosate is reviewed.

Glycine↗