Search PubMed⌕ Search

Biomedical subjects

A Osman

Publications and source records attributed to A Osman.

At least 37 records · Page 2Linked to original sources
PubMed2001

Development and psychometric properties of the Student Worry Questionnaire-30.

Described are the development and initial psychometric properties (Ns = 50 and 188) of a self-report measure, the Student Worry Questionnaire-30, for use with college undergraduates. Exploratory principal components analyses (Ns = 388, 350, and 396) with oblimin rotation indicated six domains of worrisome thinking, financial-related concerns, significant others' well-being, social adequacy concerns, academic concerns, and general anxiety symptoms. The total score and scale scores showed internal consistency of .80 to .94. Also, test-retest reliability analyses (.75 to .80) support consistency of responses over 4 wk. Strong evidence for convergent validity) was indicated. Confirmatory factor analysis confirmed the fit of the 6-factor oblique model. Limitations of the present studies, and directions for research are discussed.

Adult↗
PubMed2000

Identification and functional characterization of a member of the PUR-alpha family from Schistosoma mansoni.

Schistosoma mansoni p14 gene encodes an eggshell precursor that is expressed only in vitelline cells of mature female worms in response to a male stimulus. The upstream region of the p14 gene contains several potential cis-acting regulatory sequences. We used the upstream region of the p14 gene as bait in a yeast-one-hybrid screen of a S. mansoni cDNA library to identify interacting proteins. We report the identification and characterization of a cDNA (S. mansoni PUR-alpha (SmPUR-alpha)) encoding a protein homologous to single-stranded DNA transcription activator PUR-alpha, that binds to the p14 upstream region and activates transcription of the HIS3 reporter gene in yeast. SmPUR-alpha has a predicted molecular mass of 30 kDa and shares an overall homology of 63% with mammalian PUR-alpha. The DNA binding domain of SmPUR-alpha is highly conserved. We show by gel shift assays that GST-SmPUR-alpha binds to oligonucleotides comprising the p14 upstream region. SmPUR-alpha binds preferentially to single-stranded DNA and also binds RNA. Unlike the mammalian homologue, SmPUR-alpha exhibits little specificity for the PUR element GGn, but shows strong preference for a sequence containing alternating pyrimidines. Our data support that SmPUR-alpha is a single-copy gene and through reverse transcriptase-polymerase chain reaction and in situ hybridization, we show that SmPUR-alpha is constitutively transcribed in many cell types and thus likely plays a role as a general transcription activator in schistosomes.

Amino Acid Sequence↗
PubMed2000

Mechanisms of speed-accuracy tradeoff: evidence from covert motor processes.

Speed-accuracy tradeoff (SAT) refers to the inverse relation between speed and accuracy found in many tasks. The present study employed reaction times (RTs) and movement-related brain potentials arising during the RT interval (lateralized readiness potentials; LRPs) to examine the mechanisms by which people control their position along an SAT continuum. Many models of SAT postulate that changes in position across conditions (macro-tradeoffs) and trial-by-trial variations within conditions (micro-tradeoffs) are mediated, at least in part, by the same mechanisms. These include: (1) all models that postulate mixtures of guesses and accurate responses and (2) some models postulating decision criterions applied to accumulating evidence or response tendencies. Such models would seem to be rejected for conditions under which macro- and micro-tradeoffs can be shown to involve no stages of RT in common. Under the present conditions, the two types of SAT produced additive effects on RT, with the macro-tradeoff involving only that portion of the RT interval occurring after LRP onset and the micro-tradeoff involving only that portion before LRP onset. These findings imply that the two types of SAT arose during different serial stages of RT and that the macro-tradeoff involved only stages occurring after differential preparation of the two hands had begun.

Brain↗
PubMed2000

The Pain Catastrophizing Scale: further psychometric evaluation with adult samples.

Previous studies with undergraduates have provided support for the reliability and oblique three-factor structure of a new scale, the Pain Catastrophizing Scale (PCS). We examined the reliability and validity of the PCS in adult community and pain outpatient samples. The PCS showed a high internal consistency in both groups. Using data from the community sample, confirmatory factor analyses showed that the PCS taps a single construct characterized by three related dimensions. Gender differences were obtained on the PCS total score in the community and the outpatient samples. The analyses also showed significant differences between the community and the outpatient samples on the PCS total and subscales. Overall, the results showed strong evidence of criterion-related, concurrent, and discriminant validity for the PCS in the community sample. Limitations of the present study are discussed.

Adult↗
PubMed2000

Schistosoma mansoni phosphoenolpyruvate carboxykinase, a novel egg antigen: immunological properties of the recombinant protein and identification of a T-cell epitope.

In schistosomiasis mansoni, hepatic granulomatous inflammation surrounding parasite eggs is mediated by CD4(+) T helper (Th) cells sensitized to schistosomal egg antigens (SEA). We previously showed that a prominent lymphoproliferative response of CD4(+) Th cells from schistosome-infected C57BL/6 (BL/6) mice was directed against a 62-kDa component of SEA. A partial amino acid sequence of the 62-kDa component was found to be identical with one present in the enzyme phosphoenolpyruvate carboxykinase (PEPCK). Based on this sequence, a cDNA clone containing the entire coding region of PEPCK was identified, and the full recombinant Schistosoma mansoni PEPCK (rSm-PEPCK) of 626 amino acids was purified from a prokaryotic expression system. rSm-PEPCK strongly stimulated a specific T-cell hybridoma, 4E6, as well as CD4(+) Th cells from SEA-immunized BL/6 mice and from infected BL/6, CBA, and BALB/c mice. In the infected mice, rSm-PEPCK elicited significant gamma interferon production as well as, to a lesser extent, production of interleukin-2 and -5. In BL/6 and BALB/c mice, the CD4(+) Th cell response to rSm-PEPCK was greater than that directed against the egg antigen Sm-p40; conversely, CBA mice responded better to Sm-p40 than to Sm-PEPCK. A 12-amino-acid region (residues 398 to 409: DKSKDPKAHPNS) was demonstrated to contain a T-cell epitope; synthetic peptides containing this epitope significantly stimulated specific hybridoma 4E6 and polyclonal CD4(+) Th cells. The identification and characterization of immunogenic egg components will contribute to the understanding and possible control of T-cell-mediated schistosomal disease.

Amino Acid Sequence↗
PubMed2000

Insulin resistance differentially affects the PI 3-kinase- and MAP kinase-mediated signaling in human muscle.

The broad nature of insulin resistant glucose metabolism in skeletal muscle of patients with type 2 diabetes suggests a defect in the proximal part of the insulin signaling network. We sought to identify the pathways compromised in insulin resistance and to test the effect of moderate exercise on whole-body and cellular insulin action. We conducted euglycemic clamps and muscle biopsies on type 2 diabetic patients, obese nondiabetics and lean controls, with and without a single bout of exercise. Insulin stimulation of the phosphatidylinositol 3-kinase (PI 3-kinase) pathway, as measured by phosphorylation of the insulin receptor and IRS-1 and by IRS protein association with p85 and with PI 3-kinase, was dramatically reduced in obese nondiabetics and virtually absent in type 2 diabetic patients. Insulin stimulation of the MAP kinase pathway was normal in obese and diabetic subjects. Insulin stimulation of glucose-disposal correlated with association of p85 with IRS-1. Exercise 24 hours before the euglycemic clamp increased phosphorylation of insulin receptor and IRS-1 in obese and diabetic subjects but did not increase glucose uptake or PI 3-kinase association with IRS-1 upon insulin stimulation. Thus, insulin resistance differentially affects the PI 3-kinase and MAP kinase signaling pathways, and insulin-stimulated IRS-1-association with PI 3-kinase defines a key step in insulin resistance.

Adult↗
PubMed2000

Why young people do not kill themselves: the reasons for living inventory for adolescents.

Assessed the reliability, validity, and predictive power of a new measure, the Reasons for Living Inventory for Adolescents (RFL-A; Osman et al., 1998). A group of 206 (101 boys and 105 girls) adolescent psychiatric inpatients completed the RFL-A, Minnesota Multiphasic Personality Inventory for Adolescents (Butcher et al., 1992), and a packet of self-report measures. Additional information about the patients including diagnosis and suicide status were obtained from their medical records. It was determined that the RFL-A is a valid and reliable measure of adolescent suicide risk potential. Additionally, the RFL-A possesses better predictive power than the Beck Hopelessness Scale (Beck, Weissman, Lester, & Trexler, 1974). A discussion of the clinical and research utility of the RFL-A is included along with suggestions for future research.

Adolescent↗
PubMed2000

The multi-attitude suicide tendency scale: further validation with adolescent psychiatric inpatients.

The present study was designed to examine the construct validity and psychometric properties of the Multi-Attitude Suicide Tendency Scale in adolescent psychiatric inpatients. This new scale has four subscales: attraction to life, repulsion by life, attraction to death, and repulsion by death. Confirmatory factor analysis of the scale items provided support for the fit of the 28-item, four-factor model. Results of logistic regression analyses revealed that high scores on the repulsion by life and the attraction to death subscales were useful in assessing the risk for suicide attempts. Results of the hierarchical regression analysis showed that high repulsion by life and low attraction to life subscale scores contributed to the prediction of scores on the suicide probability scale. We also examined gender differences on the four subscales and the psychological correlates of each subscale.

Adolescent↗
PubMed1999

Characterization of the Ras homologue of Schistosoma mansoni.

Ras is a member of a super-family of guanine-binding or G-proteins. Ras functions as a molecular switch in the transduction of signals generated by the activation of a variety of cell surface receptors and relays the signals to downstream effectors. Little is known about signal transduction in schistosomes. In order for Schistosoma mansoni to survive different immune responses triggered by the host as well as to migrate from the site of penetration at the skin to the final destination in portal circulation, they must receive signals from the host environment and respond to them in a way that allows their survival. We have isolated the schistosome Ras cDNA by using sequence information of the schistosome Ras homologue submitted to the Genbank database. Analysis of the encoded peptide revealed 81% identity and 92% similarity with K-Ras from various species. Ras is a single copy gene as determined by quantitative hybridization experiments. The cDNA was cloned into pGEX-4T and the expressed peptide was used to generate specific antibody reagents. Affinity purified antibodies identified a 23 kDa native protein that localizes to the subtegument. Ras is not associated with the tegument. Ras is expressed in all the developmental stages of the parasite. However, Ras is over-expressed in female worms compared to males. Schistosome Ras was also shown to be post-translationally modified by addition of farnesyl isoprenoid moiety to the cysteine residue in the C-terminal box. Using a schistosome extract in vitro SmRas farnesylation was inhibited by the farnesyl transferase inhibitor, FTI-277, at concentrations comparable to those required to inhibit K-Ras processing. These initial studies on signal transduction in schistosomes should provide a solid basis for improving our understanding of schistosome-host interactions.

Alkyl and Aryl Transferases↗
PubMed1999

Identification of a cDNA encoding a retinoid X receptor homologue from Schistosoma mansoni. Evidence for a role in female-specific gene expression.

Schistosoma mansoni, a multicelluar eukaryotic blood fluke, is a major cause of morbidity worldwide in humans. The study of female parasite growth, development, and gene regulation is important because the eggs produced are responsible for the pathogenesis observed in schistosomiasis. p14, an eggshell precursor gene expressed only in sexually mature females in response to a male stimulus, is a model for female-specific gene regulation. The upstream region of the p14 gene shares sequences present in insect genes known to be regulated in a sex-, temporal-, and tissue-specific manner by members of the steroid receptor superfamily. Herein, we report the identification and characterization of a cDNA that encodes the S. mansoni (Sm) RXR homologue. Sequence analysis predicts and Western blot analysis confirms the synthesis of a 74-kDa protein, the largest member of the RXR family reported to date. We show by electrophoretic mobility shift assay analysis that SmRXR binds to cis-elements of the p14 gene including a direct repeat that follows the "3-4-5" rule of binding elements recognized by members of the steroid receptor superfamily. Furthermore, we demonstrate that SmRXR can act as a transcription activator in the yeast one-hybrid system. Through quantitative reverse transcriptase-polymerase chain reaction, we show that the SmRXR gene is constitutively expressed and thus must play multiple roles throughout the schistosome life cycle.

Amino Acid Sequence↗
PubMed1999

Cortico-spinal inhibition reflects time but not event preparation: neural mechanisms of preparation dissociated by transcranial magnetic stimulation.

Changes in cortico-spinal excitability related to time and event preparation were investigated by transcranial magnetic stimulation (TMS) of the motor cortex during the foreperiod of a movement-precuing task. Subjects performed a four alternative choice reaction time (RT) task involving a button-press with the index or middle finger (FI) of the left or right hand. Advance information about the to-be-signaled response was provided by a precue, which preceded the response signal by a 1 s foreperiod. The precue either indicated the hand (right or left) or FI (index or middle) with which the response would be executed or was uninformative. TMS was delivered to the left or right cortical hand area at one of five possible times during the foreperiod: -1000, -500, -333, -166 or 0 ms prior to the response signal. Surface EMG activity from a prime mover involved in flexion of the response FIs (Flexor digitorum superficialis) was used to measure the magnitude of the motor evoked potential (MEP) elicited by TMS. Cortico-spinal excitability--as assessed by the magnitude of the MEP evoked in the target muscle contralateral to the stimulated hemisphere--progressively decreased during the foreperiod. The identity of the precued responses, however, had no effect on MEP magnitude. These results suggest that preparation to respond at a particular time inhibited excitability of the cortico-spinal tract, while advance preparation to perform specific responses affected more central structures only.

Adult↗
PubMed1999

Accelerated allograft degeneration after aortic valve endocarditis.

Early calcification of aortic allografts is usually seen in children less than 3 years of age. We describe a case of a 22-year-old intravenous drug user who developed calcific aortic valve stenosis less than 3 years after an allograft root replacement for endocarditis.

Adult↗
PubMed1999

Solid state stability of ketoprofen in the presence of different excipients.

Physical mixtures of ketoprofen (KT) were prepared using different excipients, namely, lactose, mannitol, sorbitol, beta-cyclodextrin, polyvinylpyrolidone (PVP) K30, polyethyleneglycol (PEG) 20,000 and urea in a ratio of 2:1 (drug/excipient). The prepared samples as well as KT alone were stored at 40, 50 and 60 degrees C in sealed glass vials for 12 weeks. The fresh and stored samples were subjected to physical examination and instrumental analysis including m.p., IR and dissolution rate. KT without additives was found to be physically stable or when mixed with either lactose, mannitol, sorbitol or beta-cyclodextrin for 12 weeks at 60 degrees C. The m.p. of the drug alone or in presence of these excipients did not change. Also IR showed no change. On the other hand, KT mixtures with PVP K30, PEG 20,000 or urea were physically unstable on storage at 40, 50 and 60 degrees C. Their m.p. were found to decrease; the IR curves were also changed. All the tested excipients enhanced the dissolution of KT from its physical mixtures and could be arranged according to the extent of dissolution as follows: Lactose = Mannitol > beta-cyclodextrin > PVP K30 = Urea > Sorbitol > PEG 20,000.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

[Seasonal migration: a case control study of malaria prevention in Sabah].

Malaria is an infectious disease that remains the main health problem in Tawau, Sabah. A case control study was carried out in the district to determine the influence of seasonal migration on malaria occurrence. Respondents consisted of 142 cases who were randomly selected from the reported cases in 1996 and they were pair-matched with 142 controls from the same villages by age and sex. The results showed that malaria occurrence was significantly associated with movement to the jungle, use of preventive measures during migration and frequency of using treated bednets (p < 0.05). The risk of individuals migrated to the jungle was 6 times as compared to those who do not (unadjusted Odd Ratio = 5.50, 95% CI 1.16-35.89) and they were more likely to get the infection if they did not use bednets (OR = 3.57, 95% CI 1.57-9.06). Health promotion campaign on the use of bednets especially during short term migration should be given priority in any malarial intervention program.

Adult↗
PubMed1998

Clinical utility of the MMPI-A content scales and Harris-Lingoes subscales in the assessment of suicidal risk factors in psychiatric adolescents.

This study of 143 inpatient adolescents (68 boys and 75 girls) investigated the clinical utility of the MMPI-A in assessing suicidal risk factors by examining the unique contribution of the content scales and Harris-Lingoes subscales beyond what is provided by the basic clinical scales. The results of the regression analyses indicated that for boys, the Depression, Psychopathic Deviate and Hypomania scales; Alienation and Anxiety content scales: and Subjective Depression. Self Alienation, Imperturbability, and Amorality Harris-Lingoes subscales contributed significantly to the prediction of suicide probability. For girls, the Depression, Psychopathic Deviate, and Hypomania scales; Family Problems, Conduct Problems, School Problems, Depression, and Social Discomfort content scales; and the Subjective Depression, Self Alienation, Psychomotor Acceleration, and Imperturbability Harris-Lingoes subscales contributed significantly to the prediction of suicide probability.

Adolescent↗
PubMed1998

The Reasons for Living Inventory for Adolescents (RFL-A): development and psychometric properties.

The role of adaptive beliefs and attitudes against suicide has not been given adequate attention in the clinical or assessment literature. This article reports on the development and initial psychometric properties of a 32-item self-report inventory, the Reasons for Living Inventory for Adolescents (RFL-A). In Phase 1, we used exploratory and confirmatory factor analyses to identify five correlated factors: Future Optimism, Suicide-Related Concerns, Family Alliance, Peer Acceptance and Support, and Self-Acceptance. In Phase 2, we cross-validated the 5-factor oblique model in a different group of adolescents recruited from two high schools. In addition, we examined evidence for convergent, discriminant, and construct validities. The coefficient alpha indices for the RFL-A total and scales were satisfactory. In Phase 3, we evaluated additional evidence of reliability and validity using samples of high school and psychiatric inpatient adolescents. The results suggest that the RFL-A is a short, reliable, and valid measure that is potentially useful in the assessment of adolescent suicidal behavior.

Adolescent↗