Temperature-gradient gel electrophoresis as a screening tool for polymorphisms in multigene families

Information about sequence variability between different copies of a multigene family is indispensable for understanding the evolutionary mechanisms acting on multigene families. However, their high copy number has been a major obstacle to systematic analysis. Exemplified by the internal transcribed spacer 1 (ITS1) of the rDNA in Drosophila melanogaster, it is shown how temperature gradient gel electrophoresis (TGGE) can be used to study sequence polymorphisms in a multigene family. Experimental conditions influencing the melting behavior of the ITS1 fragment are discussed as well as discrepancies between observed and calculated melting patterns.     

Use of the health history as a psychiatric screening tool

Epidemiologic supervision of P. aeruginosa infections is a daily care for microbiologists. The aim of this study is to evaluate quantitative antibiogram, which compare strains by calculation of euclidian distances from inhibition zone diameters on agar, compared with pulse field gel electrophoresis (PFGE) results. 53 isolates of P. aeruginosa obtained from bronchial secretions of 26 patients in intensive care unit are typed by conventional disk diffusion test on agar with 11 usual antibiotics. Dendrogram of euclidian distances is performed by Taxotron computer program (P.A.D. Grimont, Institute Pasteur, Paris); results are compared with 53 PFGE patterns after restriction with Spe I (Genepath system, BIO-RAD). Quantitative antibiogram has a high discriminatory power for beta-lactamin resistant strains: 27 isolates from 11 patients clustered in 5 types where PFGE discerned 5 patterns. The discriminatory power is low for beta-lactamin sensible strains: 26 isolates from 15 patients clustered in 8 types where PFGE discerned 19 patterns, but serotyping method combined with quantitative antibiogram restore a high disriminatory power for beta-lactamin sensible strains.     

Evaluation of an adenosine 5'-triphosphate assay as a screening method to detect significant bacteriuria

The bioluminescent reaction of adenosine 5'-triphosphate (ATP) with luciferin and luciferase has been used in conjunction with a sensitive photometer (Lab-Line's ATP photometer) to detect significant bacteriuria in urine. This rapid method of screening urine specimens for bacteriuria was evaluated by using 348 urine specimens submitted to the clinical microbiology laboratory at the University of Minnesota Hospitals for routine culture using the calibrated loop-streak plate method. There was 89.4% agreement between the culture method and the ATP assay, with 7.0% false positive and 27.0% false negative results from the ATP assay using 10(5) organisms/ml of urine or greater as positive for significant bacteriuria and less than 10(5) organisms/ml as negative for significant bacteriuria.     

Usefulness of hybrid capture HPV DNA assay as a diagnostic tool for human papillomavirus infection

The purpose of this study was to determine the usefulness of the hybrid capture HPV DNA assay, a new nonradioactive solution hybridization assay, as a diagnostic tool for human papillomavirus infection. In a total of 234 women, samples for the hybrid capture assay and polymerase chain reaction (PCR) assay were obtained by wiping a swab across the cervix and external os (either a Dacron swab or a cotton swab was used). The papanicolaou smear test (Pap smear) was carried out on all 234 women. Tissue samples for biopsy were obtained by colposcopy from 118 of the women. Fisher exact test was used for statistical analyses. Using the hybrid capture assay, HPV DNA of high- and intermediate-oncogenic-risk type was detected in 23 (13.9%) of 166 samples from women with Pap smear Class I or II, and 48 (70.6%) of 68 with Pap smear Class III, IV or V (p < 0.0001). The HPV DNA type was detected in 18 (29.0%) of 62 samples from those with no evidence of cervical intraepithelial neoplasia and 44 (78.6%) of 56 with cervical intraepithelial neoplasia or squamous cell carcinoma (p < 0.0001). Correlation of the test results between the hybrid capture test and PCR was determined by using the 217 samples in which both test results were available (PCR test results were not obtainable in 17 samples. When PCR is set as a gold standard, the hybrid capture test has high sensitivity (74.6%) and specificity (92.7%). These findings suggest that the hybrid capture HPV DNA assay is a useful method for diagnosing HPV infection in the clinic.     

Molecular dynamics simulation of MHC-peptide complexes as a tool for predicting potential T cell epitopes

The class I major histocompatibility complex-encoded HLA-B*2705 protein was simulated in complex with six different peptides exhibiting unexpected structure-activity relationships. Various structural and dynamical properties of the solvated protein-peptide complexes (atomic fluctuations, solvent-accessible surface areas, hydrogen bonding pattern) were found to be in qualitative agreement with the available binding data. Peptides that have been experimentally shown to bind to the protein remained tightly anchored to the MHC molecule, whereas nonbinders were significantly more weakly complexes to the protein and progressively dissociate from it at their N- and C-terminal ends. The molecular dynamics simulations emphasize the unexpectedly important role of secondary anchors (positions 1 and 3) in influencing the MHC-bound conformation of antigenic nonapeptides. Furthermore, it confirms that dominant anchor residues cannot solely account for peptide binding to a class I MHC molecule. The molecular dynamics method could be used as a complementary tool to T cell epitope predictions from the primary sequences of proteins of immunological interest. It is better suited to MHC proteins for which a crystal structure already exists. Furthermore, it may facilitate the engineering of T cell epitopes as well as the rational design of new MHC inhibitors designed to fit optimally the peptide binding cleft.     

An in vitro messenger RNA binding assay as a tool for identifying hybridization-competent antisense oligonucleotides

Targeting, use of appliances, and standards of outcome for General Dental Service orthodontic cases collected between 1990 and 1991 were compared with a sample of cases from an earlier study, collected between 1987 and 1988, using the PAR index and IOTN. Comparisons are made generally and in relation to the changes in prior approval regulations for cases started since October 1987. More lower-need cases were treated, but there were no more "unnecessary' treatments and there has been a limited improvement in outcomes, as assessed by the indices, associated with increased use of fixed appliances since 1987. Prior approval appeared to give no tangible benefits in terms of levels of unnecessary treatment or quality of outcome.     

Tympanometry as a screening tool in the NICU: is it effective?

This study assess the usefulness of the tympanogram as a screening tool for identifying otitis media and serous otitis media in preterm infants. Twenty-six infants from the NICU were assessed on the same day by two examiners using tympanometry and pneumatic otoscopy. The results were recorded separately and compared after all infants were tested. An audiologist independently interpreted each of the tympanogram strips. There was very little agreement between tympanometry and otoscopy results. The tympanogram was not found to be a repeatable or a reliable screening tool for assessing otitis media and serous otitis media in the NICU population. It was concluded that the NICU nurse must be aware of the signs and symptoms of otitis media and serous otitis media. If this diagnosis is raised for an infant in the NICU, careful visualization of the tympanic membrane should be carried out along with referrals to ear, nose, and throat and audiology experts.     

Oxygen electrode syringe as an instrument for determining oxygen-hemoglobin dissociation curves

A new instrument is described which simplifies the measurement of the oxygen-hemoglobin dissociation curve, using small volumes of blood. An oxygen electrode, as the plunger of a syringe accommodating increasing volumes of blood at predetermined levels of saturation with oxygen, measures the amount of dissolved oxygen in the plasma, which is proportional to the gas tension.     

Lichens as a tool for biogeochemical prospecting

The heavy metal content in lichens and vascular plants from abandoned copper mining areas, Gerakario (Kilkis) and Megali Panagia (Chalkidiki), have been compared with metal content in soil in order to assess their efficiency to accumulate five metals (Cu, Mn, Pb, Zn, and Cr). The average metal content in the mineralized soil of Gerakario was, in descending order, Cu, Mn, Pb, Zn, and Cr, and in Chalkidiki it was Cu, Mn, Cr, Pb, and Zn. The epilithic lichens (Neophuscelia pulla) accumulated the highest amount of Cu and Pb, and Xanthoparmelia taractica accumulated the highest amount of Zn. All the lichens revealed significant (P < 0.05) correlation between Cu content in soil and that in thalli. Out of five metals studied, four (Cu, Pb, Mn, and Cr) in the epigeic lichen Cladonia convoluta, two (Cu and Mn) in both epilithic lichen N. pulla and X. taractica, and one (Pb) in vascular plant Minuartia (root) were significantly (P < 0.05) correlated between their metal content in plant tissue and in soil. Further, discoloration of C. convoluta with higher Cu concentrations adds a visible clue for biogeochemical exploration. Thus, lichens along with other symptomatic species will help in locating mining areas.     

Protein engineering as a tool for crystallography

A questionnaire survey of 260 health care workers from 13 randomly selected health care facilities was undertaken. Their knowledge, attitude, belief and blood handling practices regarding HIV/AIDS were enquired about. Virtually all (99.0%) respondents had heard about AIDS but only 57.0% had seen an AIDS patient before. Although 83.0% knew that AIDS is caused by a virus, a high proportion still confuses mode of transmission with causative agent. Deficient knowledge was exhibited when asked about groups of people who were at a higher risk of contracting HIV and AIDS: Only 54.6% and 51.5% identified homosexuals and i.v. drug users as being at a higher risk. Almost all (97.0%) of our respondents claimed to have been more careful in their blood handling practices since the emergence of AIDS, 68.5% wore gloves for all procedures involving handling of blood and 28.5% sometimes although as many as 30.4%, 40.4% and 18.1% do not wear gloves for cleaning up blood stained materials, nursing procedures and taking obstetric delivery respectively. It was evident from their responses that not all the health workers knew the correct method for disposing of used bloodstained instruments and left-over blood samples and neither were they all adhering to the safety guidelines recommended for handling these materials. Education of all health care workers in Nigeria on the Universal Precautions Guidelines issued by the Centers for Disease Control (CDC) in 1987 regarding blood, body fluids and contaminated instruments' handling precautions is urgently recommended.     

Evaluation of a tool for developmental disorder screening in 4-year-old children

With the aim of helping physicians working in a "Mother and Infant Protection Service" (PMI) in their mission of children's development difficulties screening, authors tried to assess performances of a clinical tool including parental informations and standardized tests. The whole four years old children going at school in a canton of Calvados department were independently examined by a PMI doctor using the tool to be estimated and by a specialized service working from a beforehand established protocol. For the language disorders on the one hand and the adaptation on the other hand, this evaluation shows a significant correlation between the PMI screening and the specialists one's: the sensitivity of the PMI examination is about 70% for those two types of difficulties with a positive predictive value respectively 28% and 57%. However the tool appears less reliable for the psychomotor disorders screening: only one quarter of the children who require a specialized investigation about these problems have been detected by the PMI screening. A filing and a selection of the questionnaire items should permit to improve the efficiency of this tool.     

The psychiatric review of symptoms: a screening tool for family physicians

The psychiatric review of symptoms is a useful screening tool for identifying patients who have psychiatric disorders. The approach begins with a mnemonic encompassing the major psychiatric disorders: depression, personality disorders, substance abuse disorders, anxiety disorders, somatization disorder, eating disorders, cognitive disorders and psychotic disorders. For each category, an initial screening question is used, with a positive response leading to more detailed diagnostic questions. Useful interviewing techniques include transitioning from one subject to another rather than abruptly changing subjects, normalization (phrasing a question to convey to the patient that such behavior is normal or understandable) and symptom assumption (phrasing a question to imply that it is assumed the patient has engaged in such behavior). The psychiatric review of symptoms is both rapid and thorough, and can be readily incorporated into the standard history and physical examination.     

Exercise in an hypoxic environment as a screening test for ischaemic heart disease

Submaximal and maximal exercise testing have been used to predict coronary events but these tests do not give reliable information regarding employability of subjects with abnormal electrocardiogram. In 30 subjects with stabilized ischaemic heart disease (Group A) and 70 subjects with abnormal resting electrocardiogram (Group B), resting electrocardiograms--at ground level and at a simulated height of 4592 m (15000 ft)--after 40-min exposures were recorded. The double Master's two-step exercise test (DM) was performed at ground level as well as at stimulated height (DMH). In the ischaemic group, exercise combined with hypoxia did not yield better results than exercise alone; but among the asymptomatic subjects, exercise in an hypoxic environment gave significantly better results than exercise alone (p less than 0.005) or hypoxia alone (p less than 0.01). Those with negative responses to the test have been employed on strenous duties, including employment at high altitude for the last 3 years. None of them have manifested any objective or subjective evidence of ischaemic heart disease. DM exercise testing in an hypoxic environment is a reliable method to assess subjects with abnormal electrocardiogram and evaluate their functional status.     

Validation of a French version of an informant-based questionnaire as a screening test for Alzheimer's disease

BACKGROUND: Development of informant-based screening tests for dementia is an emerging field. The reliability and validity of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), an instrument that screens for dementia in general, have been established. We conducted a study to validate a French version of the IQCODE as a screening test for Alzheimer's dementia in the elderly living in the community. METHOD: In the Canadian Study of Health and Aging, subjects were screened in their own homes using the modified Mini-Mental State Exam (3-MS). Those who screened positive, along with a sample of subjects who screened negative, were referred for a complete clinical examination. In Quebec, an informant was asked to complete the French version, IQCODE(F), at that time. Based on the final clinical diagnoses, performances of the IQCODE(F) and Mini-Mental State Examination (MMSE, converted from 3-MS) in screening for Alzheimer's disease were evaluated. RESULTS: Of the 237 subjects, the mean IQCODE (F) score was 3.4 (s.d. = 0.6), on a 5-point scale (1 = improvement in condition over the past 10 years, 5 = marked deterioration, 3 = no change). The mean MMSE score was 23.1 (s.d. = 4.5). The scores on the two scales were correlated (r = -0.44, P < 0.001). The IQCODE(F) scores were unrelated to education (r = -0.07, P > 0.3) in contrast to the MMSE scores (r = 0.28, P < 0.001). With respect to a diagnosis of probable Alzheimer's disease, the IQCODE(F) (cut-off point 3.6) had a sensitivity of 75% and a specificity of 95.6%. The sensitivity and specificity of the MMSE (cut-off point 23) were 70% and 82.3% respectively. CONCLUSION: The findings of the IQCODE(F) are consistent with those of the English version in correlation with the MMSE and apparent freedom from educational bias. The IQCODE is superior to the MMSE as a screening test for probable Alzheimer's disease in the elderly living in the community. It may be a useful addition to the screening tests already available, especially for the less well educated.     

Use of the Zung Self-Rating Depression Scale in cancer patients: feasibility as a screening tool

The impact of a traumatic brain injury on the family of the injured person is just beginning to be explored. In the current study, 61 primary caregivers were contacted at 1 year following injury. They completed the Relative and Friend Support Index, Social Support Index, Trauma Complaints List and the Life Change Question. The majority of caregivers indicated at least mild negative life change following the brain injury. Greater social support was correlated with less life change and greater injury severity was correlated with negative life change. Neither of these relationships was found to be significant at the 0.05 level. A significant positive correlation was found between caregivers' perception of deficits and the degree of negative life change. Perceived deficits accounted for the greatest amount of variance in life change followed by relative and friend support when all variables were entered into a stepwise regression. Further analyses indicated that the most significant factor of the Trauma Complaints List in predicting life change may be problems with cognition, which accounted for a significant amount of the variance in life change. Implications for counselling and further research regarding caregivers of persons with brain injury are discussed.     

Fluoresceinthiocarbamyl-insulin: a potential analytical tool for the assay of disulfide bond reduction

We describe the synthesis of fluorescent derivatives of bovine pancreas insulin and its use as substrates of disulfide bond reduction in a spectrofluorometric assay. Amino groups of insulin were chemically modified with fluorescein isothiocyanate and proteins bearing one, two and three fluorescent groups were purified by ion-exchange chromatography. Upon incubation with dithiothreitol, di- and tri-fluoresceinthiocarbamyl-insulin evinced the highest and the lowest enhancement of fluorescence emission, whereas the mono-substituted protein had intermediate enhancement. Using di-fluoresceinthiocarbamyl-insulin, the reliability of this novel feature for the estimation of disulfide bond cleavage was assessed by (i) the separation of two fluorescent bands using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, (ii) the linear response of the fluorescence signal within a range from 0.04 to 1 microM, and (iii) the correlation of the rate of fluorescence enhancement with concentrations of dithiothreitol ranging from 0.1 to 5 mM. Moreover, di-fluoresceinthiocarbamyl-insulin was a sensitive oxidant when the catalytic capacity of thioredoxin and protein disulfide isomerase was analyzed in the presence of dithiothreitol or glutathione, as reductants. On this basis, di-fluoresceinthiocarbamyl-insulin constitutes an analytical tool to test the capacity of biochemical preparations in the reduction of disulfide bonds.     

The importance of statistics as a tool for management and as a yardstick for valuations

This article explains the importance of comparing statistics from year to year, especially when analyzing a practice for purchase, sale, partnership, or management. This is an invaluable tool that becomes a yardstick for measurement and should never be omitted or dispensed with.     

Community-based urine screening for Chlamydia trachomatis with a ligase chain reaction assay

BACKGROUND: Urine tests for Chlamydia trachomatis permit expansion of screening beyond traditional clinic environments. Prevention of infection in teenagers is a high priority. OBJECTIVE: To define the prevalence of C. trachomatis among teenagers by using the ligase chain reaction assay on urine specimens and to evaluate leukocyte esterase testing of urine specimens as an indicator of infection. DESIGN: Cross-sectional study. SETTING: An adolescent clinic, a juvenile detention facility, seven school-based clinics, and three community-based youth organizations in Seattle, Washington. PARTICIPANTS: 10,118 sexually active teenagers and young adults. MEASUREMENTS: Chlamydia trachomatis infection detected in urine specimens by ligase chain reaction assay and leukocyturia detected by leukocyte esterase testing. RESULTS: The prevalence of chlamydial infection among female participants was 8.6% and declined with increasing age; among male participants, it was 5.4% and increased with increasing age. In female participants, independent predictors of infection were being 17 years of age or younger (odds ratio [OR], 1.49), having had two or more sex partners in the previous 2 months (OR, 1.61), and having genitourinary symptoms (OR, 1.46). In male participants, independent predictors were being of nonwhite race or ethnicity (OR, 2.00 to 3.08), having had two or more sex partners in the previous 2 months (OR, 1.57), and having used a condom during the most recent sexual encounter (OR, 0.67). For identifying infection in male participants, the sensitivity of leukocyte esterase testing was 58.9%, the specificity was 94.9%, the positive predictive value was 38.4%, and the negative predictive value was 97.7%. CONCLUSIONS: Chlamydial infection is common in teenagers and young adults in community settings. The urine ligase chain reaction assay will permit widespread screening for C. trachomatis, but leukocyte esterase testing had low sensitivity for selecting persons for screening with this assay. Indicators of chlamydial infection differed substantially in male and female participants.     

Nurses'' logs as an evaluation tool for school-based violence prevention programs

AIM: To develop a reliable, machine-readable coding system for dental appliances. METHODS: Incorporation of two-dimensional bar codes and matrix codes into a range of dental appliances using printed thermal substrates and laser-etched ceramic discs. RESULTS: Problems including reaction of thermal substrates with methyl methacrylate monomer, loss of code clarity, limited areas available for bar codes, difficulty in scanning opaque pigmented acrylic resin and palatal and lingual surfaces were overcome using 4 mm2 data matrix codes etched onto ceramic discs. CONCLUSIONS: Reliable automatic identification of dental appliances was achieved using laser-etched matrix codes. Further development is necessary in relation to optimisation of code size, encryption, scanners and maintenance of code readability over time.