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A Stevens

Publications and source records attributed to A Stevens.

At least 91 records · Page 5Linked to original sources
PubMed1999

Comparison of MMPI-A, Marks and Briggs, and MMPI-2 norms for juvenile delinquents.

A study was conducted to compare scores of juvenile delinquents on the new MMPI-A to previous research and to compare 3 sets of norms for adolescents: the MMPI-A, the Marks-Briggs adolescent norms, and the MMPI-2 adult norms. Subjects, 11 boys and 11 girls, were hospitalized adolescents, aged 14 to 17 years, with a history of conduct problems. Analysis of MMPI-A scale scores for boys indicated elevated T-score means on scales F (64), Hs (64), Pd (65), Pa (68), Pt (68), Sc (70), and Ma (66). Mean T scores for girls on the MMPI-A were elevated on scales of F (62), Pd (64), and Sc (62). The findings that the mean T score for scales Pd, Sc, and Ma are elevated for this population is consistent with previous research on juvenile delinquents. In general, the MMPI-A scale elevations were lowest, followed by the Marks-Briggs norms. The MMPI-2 T-score means were the most elevated. One of the limitations of the present investigation is an extremely small sample. Until further research is conducted on larger samples, clinicians concerned about the different norms are encouraged to plot MMPI-A scores on both adolescent and adult norms. It is also recommended that the MMPI-A be included as part of an assessment battery with other objective tests, clinical observation, and patient report.

Adolescent↗
PubMed1999

The false-negative fraction: a statistical method to measure the efficacy of cervical smear screening laboratories.

The false-negative fraction (FNF) is emerging as a statistical parameter that may be used to evaluate the efficacy of Papanicolaou smear screening laboratories. Our objectives for this paper are to acquaint non-laboratorians with this important measurement and to measure the FNF of the Air Force Cyto-center (AFCC) at the Armed Forces Institute of Pathology in Washington, DC. The FNF is defined as estimated false negatives divided by (true positives plus estimated false negatives). Most often, the number generated is multiplied by 100 and expressed as a percent. We have determined the FNF of the AFCC to be 3.7%. This value compares favorably with most others reported in the medical literature.

Aerospace Medicine↗
PubMed1998

Comparative analyses of the secondary structures of synthetic and intracellular yeast MFA2 mRNAs.

The overall folded (global) structure of mRNA may be critical to translation and turnover control mechanisms, but it has received little experimental attention. Presented here is a comparative analysis of the basic features of the global secondary structure of a synthetic mRNA and the same intracellular eukaryotic mRNA by dimethyl sulfate (DMS) structure probing. Synthetic MFA2 mRNA of Saccharomyces cerevisiae first was examined by using both enzymes and chemical reagents to determine single-stranded and hybridized regions; RNAs with and without a poly(A) tail were compared. A folding pattern was obtained with the aid of the MFOLD program package that identified the model that best satisfied the probing data. A long-range structural interaction involving the 5' and 3' untranslated regions and causing a juxtaposition of the ends of the RNA, was examined further by a useful technique involving oligo(dT)-cellulose chromatography and antisense oligonucleotides. DMS chemical probing of A and C nucleotides of intracellular MFA2 mRNA was then done. The modification data support a very similar intracellular structure. When low reactivity of A and C residues is found in the synthetic RNA, approximately 70% of the same sites are relatively more resistant to DMS modification in vivo. A slightly higher sensitivity to DMS is found in vivo for some of the A and C nucleotides predicted to be hybridized from the synthetic structural model. With this small mRNA, the translation process and mRNA-binding proteins do not block DMS modifications, and all A and C nucleotides are modified the same or more strongly than with the synthetic RNA.

Base Sequence↗
PubMed1998

Decreased duration and altered topography of electroencephalographic microstates in patients with panic disorder.

The topography and temporal sequence of scalp electrical fields were analyzed by adaptive segmentation of the continuous electroencephalogram (EEG) in 27 patients with panic disorder and 28 control subjects during rest phases and during the viewing of a neutral (mushroom) or an emotionally relevant (casualty) picture. The results indicate decreased duration of brain microstates in panic patients during all conditions. Comparison of the resting phases with the viewing conditions revealed a significant acceleration of EEG microstates in both the patients and the control subjects. Patients and control subjects differed in the topography of the fields during rest: control subjects showed a left-anterior/right-posterior orientation, while panic patients showed a predominantly right-anterior/left-posterior orientation. Neither group displayed any topographic changes when viewing the mushroom picture. However, when viewing the anxiety-specific casualty picture, panic patients shifted fields in a different way than did control subjects. Centroid topography does not permit clear localization of the cortical generators. It is concluded that panic patients show a generally increased cortical activation compared with healthy control subjects, and activate different neuronal arrays when viewing an anxiety-specific stimulus.

Adult↗
PubMed1998

Endonucleolytic cleavage of RNA at 5' endogenous stem structures by human flap endonuclease 1.

Structure-specific nucleases called 5' flap endonucleases cleave unannealed 5' arms of template-primer DNA model substrates at the start of the duplex and are involved in Okazaki fragment processing during DNA synthesis. To determine the possible use of the enzymes in RNA structure analysis, the cleavage of synthetic and native RNAs was examined using flap endonuclease 1 (Fen1) of HeLa cells. RNAs are cleaved at about 20% of the rate of DNA model substrates, and most of the cleavage sites are within 200 nucleotides of the 5' end. Hydrolysis of MFA2 mRNA of yeast shows that the cleavages are at the start of five possible stem structures of a folded secondary structure predicted on the basis of both chemical and enzymatic structure probing. 16S ribosomal RNA of Escherichia coli is cleaved at several 5' stem structures of its phylogenetically predicted folded structure. This type of RNA cleavage specificity may be very useful in secondary structure analysis in the future and also may be used by cells for specific 5' end-geared RNA cleavages.

Base Sequence↗
PubMed1998

PAPNET-assisted rescreening of cervical smears: cost and accuracy compared with a 100% manual rescreening strategy.

CONTEXT: The Food and Drug Administration has recently approved several devices that use computerized image analysis to rescreen Papanicolaou (Pap) smears that have already been examined by cytotechnologists. Physicians and laboratories must decide whether the utility of these devices justifies the cost. OBJECTIVE: To determine the effectiveness and cost of PAPNET-assisted rescreening in identifying cervical abnormalities not identified by manual rescreening. DESIGN: PAPNET-assisted rescreening of 5478 Pap smears obtained in 1994 and 1995 previously identified as "within normal limits" or "benign changes" on both initial and random screening. PATIENTS: Female service members and dependents aged 12 to 88 years. SETTING: Air Force clinics in the United States and Japan. INTERVENTION: Rescreening of Pap smears by PAPNET, followed by reevaluation of abnormal smears by the consensus panel, consisting of 3 cytotechnologists and 3 pathologists. MAIN OUTCOME MEASURES: Proportion of Pap smears initially screened as normal identified as abnormal by both PAPNET and consensus panel; costs of rescreening. RESULTS: PAPNET screening identified 1614 (29%) slides requiring additional microscopic review. On further review, 448 (8% of total) had possibly abnormal cells. Ultimately, 11 of these cases were reviewed by the consensus panel for potentially atypical cells. Of these 11 cases, 5 were reclassified as atypical squamous cells of undetermined significance (ASCUS) and 1 as atypical glandular cells of undetermined significance (AGUS). No additional squamous intraepithelial neoplasia (SIL) was identified in these smears; the patient with a diagnosis of AGUS on rescreening was diagnosed as having a low-grade SIL (LSIL) on follow-up. Costs were $5825 to $33781 for each additional ASCUS or AGUS diagnosis. A cost of $17475 to $101343 is expected for each case of LSIL identified by PAPNET-assisted rescreening and not by traditional manual rescreening. CONCLUSIONS: PAPNET-assisted rescreening identified a few more cases of ASCUS than did manual rescreening, but at a relatively high cost. The costs of rescreening should be carefully compared with the expected efficacy in reducing cervical cancer mortality.

Adolescent↗
PubMed1998

Cognitive decline unlike normal aging is associated with alterations of EEG temporo-spatial characteristics.

The diagnosis of beginning dementia is based mainly on neuropsychological testing. Several measures of EEG spectral composition, coherence and complexity (correlation dimension) have been shown to correspond to cognitive function. Only a few studies have evaluated EEG changes in normal aging, and no quantitative study has addressed changes in EEG during cognitive tasks in demented elderly. In this study the quantitative descriptors of EEGs from 31 demented or cognitively impaired elderly persons, 30 healthy elderly (mean age 69 years) and 35 young controls (mean age 31 years) were compared. The EEGs were recorded during two resting conditions (eyes closed and eyes opened) and two tasks (mental arithmetics and a lexical decision). The goal of the study was to evaluate which temporal and spatial EEG descriptors change with cognitive decline and with normal aging, respectively. Cognitive categories (unimpaired, impaired, demented) were based on Structured Interview for the Diagnosis of Dementia of Alzheimer Type (SIDAM) scores. The EEGs were analysed using adaptive segmentation of continuous EEG, which quantifies the succession of distinct stable topographic voltage patterns (EEG microstates). The main findings were a significant increase in the number of ultra-short EEG microstates and, independently, a reduction in the average duration of EEG microstates in the cognitively impaired and demented patients. In addition, cognitive impairment was associated with a reduction or loss of EEG reactivity normally observed when the resting states with closed and with opened eyes are compared. No alterations in temporal or spatial EEG descriptors were found in normal aging. Cognitive tasks did not add to information already obtained during the resting states. The reduction in EEG microstate duration correlated with loss of cognitive function. Temporo-spatial analysis of EEG therefore is a useful indicator of cortical dysfunction in dementia, correlating with the degree of cognitive impairment. Normal aging seems not to be accompanied by changes in temporo-spatial EEG patterns. The data suggest that fragmentation of the electrophysiological processes underlies cognitive dysfunction in Alzheimer's disease.

Adult↗
PubMed1998

Correlation between cervical spine and temporomandibular disorders.

Neuroanatomical interconnections and neurophysiological relationships between the orofacial area and the cervical spine have been documented earlier. The present single-blind study was aimed at screening possible correlations between clinical signs of temporomandibular disorders (TMD) and cervical spine disorders. Thirty-one consecutive patients with symptoms of TMD and 30 controls underwent a standardised clinical examination of the masticatory system, evaluating range of motion of the mandible, temporomandibular joint (TMJ) function and pain of the TMJ and masticatory muscles. Afterwards subjects were referred for clinical examination of the cervical spine, evaluating segmental limitations, tender points upon palpation of the muscles, hyperalgesia and hypermobility. The results indicated that segmental limitations (especially at the C0-C3 levels) and tender points (especially in the m. sternocleidomastoideus and m. trapezius) are significantly more present in patients than in controls. Hyperalgesia was present only in the patient group (12-16%).

Adolescent↗
PubMed1998

Which are the best information sources for identifying emerging health care technologies? An international Delphi survey.

The purpose of this survey was to assess potential information sources for identifying new health care technologies. A three-round Delphi study was conducted, involving 38 selected experts who suggested and assessed potential sources by applying agreed criteria. Twenty-six potential information sources were considered. Timeliness, time efficiency, and sensitivity were important criteria in determining which were the most important sources. The eight recommended sources were: pharmaceutical journals, pharmaceutical and biotechnology companies, specialist medical journals, key medical journals, medical engineering companies, private health care providers, newsletters and bulletins from other health technology assessment agencies, and groups of expert health professionals. There is a need to use a combination of sources because the most useful sources will vary according to the type of technology under consideration.

Communication↗
PubMed1998

Early warning of new health care technologies in the United Kingdom.

In this paper we describe the present range of organizations that have a role in the early warning of new and emerging health care technologies in the United Kingdom. We discuss in more detail the processes and prioritization criteria used by the U.K. horizon-scanning project for the NHS Health Technology Assessment Programme, and the principal methods of technology identification for the horizon-scanning project are outlined. The United Kingdom plans to develop an integrated system for the identification of technologies for commercial planning, health service research prioritization, financial planning, and provision of information to policy makers, purchasers, and providers of health care.

Diffusion of Innovation↗
PubMed1998

Effect of 4-aminopyridine and single-dose methylprednisolone on functional recovery after a chronic spinal cord injury.

The demyelination process is an important factor contributing to long term sensory and motor impairments after spinal cord injury (SCI). Exposure of axonal K+ channels after demyelination may contribute to blockage of action potentials across the injury site. A K+ channel blocker, 4-aminopyridine (4-AP), has been effective in restoring some sensory and motor impairment in incomplete SCI patients. The long-term effect of this compound in chronic model of SCI is not known. In this study, after a compression injury of 50 grams in rats, a randomized treatment was initiated 3 weeks after the initial injury which was followed by daily administration of 4-AP at 2 mg/kg (n = 8), 4 mg/kg (n = 8), and 6 mg/kg (n = 8) for 4 weeks. A group of methylprednisolone (MP)-treated (30 mg/kg, n = 8) and non-treated animals (n = 8) were included for comparison. The functional motor outcome was measured in each animal at regular time points up to 4 weeks post-treatment. All animals receiving 6 mg/kg developed generalized seizure and were excluded from the study. In the other animal groups, analysis of the behavioral outcome and neuro-pathological changes were essentially similar and did not show any significant effect of treatment. Our data indicate that daily administration of 4-AP, over 4 weeks of treatment period, lacks any significant effect on axonal function in chronically injured rats. This could be due to (a) lack of significant numbers of demyelinated axons which could improve the functional outcome and (b) a treatment regimen that was not adequate to contribute to a better functional outcome. One time bolus-administration of MP at 30 mg/kg also did not ensure a better functional outcome.

4-Aminopyridine↗
PubMed1998

Expression of an AQP2 Cre recombinase transgene in kidney and male reproductive system of transgenic mice.

A transgenic mouse approach was used to examine the mechanism of principal cell-specific expression of aquaporin-2 (AQP2) within the renal collecting duct. RT-PCR and immunocytochemistry revealed that murine AQP2 was expressed in principal cells in the renal collecting duct, epithelial cells of the vas deferens, and seminiferous tubules within testis. The vas deferens expression was confirmed in rats. RT-PCR and immunocytochemistry showed that 14 kb of the human 5'-flanking region confers specific expression of a nucleus-targeted and epitope-tagged Cre recombinase in the principal cells within the renal collecting duct, in the epithelial cells of the vas deferens, and within the testis of transgenic mice. These results suggest that cell-specific expression of AQP2 is mediated at the transcriptional level and that 14 kb of the human AQP2 5'-flanking region contain cis elements that are sufficient for cell-specific expression of AQP2. Finally, renal principal cell expression of Cre recombinase is the first step in achieving cell-specific gene knockouts, thereby allowing focused examination of gene function in this cell type.

Animals↗