Biomedical subjects

J Ivan

Publications and source records attributed to J Ivan.

17 recordsLinked to original sources

PubMed2006

Spreading and mutability of Selenomonas ruminantium plasmids.

Two small plasmids from Selenomonas ruminantium strain 19D were cloned in Escherichia coli and completely characterized. Sequence comparison indicated that the plasmids are similar to those reported in genetically vaguely related S. ruminantium strain S20. Small 1.4-kb plasmids pSRD191 and pONE430 are only distantly related (approximately 30 % for deduced Rep protein amino acid sequence) but possess a short highly conserved region outside rep gene. Larger plasmids pSRD192 and pONE429 possess large identical DNA regions in an otherwise dissimilar background. Recombination is proposed as an important mechanism of evolution and spreading of S. ruminantium plasmids.

Animals↗

PubMed2005

Seasonal dynamics of antibiotic-resistant Enterobacteriaceae in the gastrointestinal tract of domestic sheep.

Considerable variation in counts of antibiotic-resistant enterobacteria in the ovine gastrointestinal tract was observed. The occurrence of ruminal and fecal isolates resistant to ampicillin (Ap), kanamycin (Km) and tetracycline (Tc) culminated in summer months, followed by rapid decline in subsequent months. Using PCR the tem1bla (Apr), aphA1 (Kmr) and tetB (Tcr) genes were found to be predominant. Under in vitro conditions all resistance genes were transferable into laboratory Escherichia coli strain with relatively high frequency (10(-3) transconjugants per recipient).

Animals↗

PubMed2001

Roadway safety in rural and small urbanized areas.

Police Accident Reports (PAR) reveal that in a 5-year period between 1993 and 1997, there were 892 crashes at 87 two lane, undivided roadway sites in Strafford County, NH, a county consisting of suburban and rural communities. The purpose of this paper is to describe: (1) logistic regression model building efforts to identify statistically significant factors that predict the probabilities of crashes and injury crashes; and (2) to use these models to perform a risk assessment of the study region. The models are functions of factors that describe a site by its land use activity, roadside design, use of traffic control devices and traffic exposure. Comparative risk assessment results show village sites to be less hazardous than residential and shopping sites. Residential and shopping sites, which are distinctly different from village sites, reside in single-purpose, land-use zones consisting mostly of single-family dwelling units and roadside shopping units with ample off-street parking. Village sites reside in multi-purpose, land-use zones permitting a combination of activities found in residential, shopping and commercial areas. They are pedestrian friendly, that is, have sidewalks and crosswalks, permit onstreet parking, have speed limits and other amenities that promote walking. Adjusted odds ratios and other comparative risk measures are used to explain why one site is more hazardous than another one. For example, the probability of a crash is two times more likely at a site without a sidewalk than at a site with one. The implications on roadway design to improve safety are discussed.

Accidents, Traffic↗

PubMed1998

The effect of biological environment on the surface of titanium and plasma-sprayed layer of hydroxylapatite.

The solubility of titanium samples with different surface coatings, i.e., hydroxylapatite (HA) powders, a two-layer coating of ZrO5+HA on a titanium substrate in solution and of tooth implants after long-term functioning in the human organism, was studied. A minimum difference in solubility of titanium samples with different surface finishes (polished or grit blasted) was established. For the HA powders and coatings, the lowest solubility was observed with a coarse-grained HA-B powder and a coating made of that powder. Clinical tests of tooth implants after long implantation times were performed. A titanium implant (implantation 12 y), a titanium implant with a two-layer coating of ZrO5+HA-A (implantation time 4 y) and a titanium implant with a two-layer coating of (Al5O3+3% TiO2)+HA-A (implantation time 6 y) were studied. The results show that the titanium surface and HA-A layers were dissolved. Nevertheless, after 6 y implantation, total removal of HA-A coating from that part of implant set into the bone, was not observed.

Journal Article↗

PubMed1996

The significance of transvaginal ultrasonographic evaluation of the cervix in women treated with emergency cerclage.

OBJECTIVE: Our purpose was to determine whether perioperative transvaginal ultrasonographic evaluation of the incompetent cervix treated with emergency cerclage is predictive of pregnancy outcome. STUDY DESIGN: Twenty-nine women who underwent emergency cerclage at 16 to 26 weeks of gestation had transvaginal ultrasonographic evaluation of the cervix within 48 hours before and after surgery and at least three times thereafter until 28 weeks of gestation. The following measurements were obtained: (1) funnel width, (2) funnel length, (3) endocervical canal length, (4) the distance between the internal and external os, (5) upper cervix (length of closed endocervical canal above the cervical cerclage), (6) lower cervix (endocervical canal length below suture), and (7) cervical index (1+ Funnel length/Endocervical canal length). Values are reported as the median in millimeters, and statistical analysis was performed by use of the Mann-Whitney U test, Wilcoxon signed-rank test, Spearman rank correlation, 2 x 2 contingency tables, and multiple regression analysis with significance set at p < 0.05. RESULTS: Cerclage procedures resulted in significant improvement in postoperative median measurements of funnel width (15 vs 4.0 mm, p < 0.0001), funnel length (29 vs 3 mm, p < 0.0001), and endocervical canal length (2 vs 27 mm, p < 0.0001). There was a significant relationship between gestational age at delivery and the following measurements: preoperative funnel width (r = -0.51, p = 0.007), postoperative endocervical canal length (r = 0.39, p = 0.04), length of the lower cervix (r = 0.39, p = 0.038), and the cervical index (r = -0.39, p = 0.038). An upper cervical length < 10 mm was a good predictor of delivery before 36 weeks of gestation, sensitivity 85.7% (12/14), specificity 66.7% (10/15), positive predictive value 70.6% (12/17), negative predictive value 83% (10/12), and Fisher's exact p = 0.008. Postoperatively all patients had upper cervical lengths < 10 mm by 28 weeks of gestation. Preoperative digital assessments of cervical dilatation before surgery did not correlate with gestational age at birth (r = -0.031, p = 0.36). CONCLUSIONS: In cases of cervical incompetence treated with emergency cerclage, perioperative transvaginal ultrasonographic assessment of the cervix reveals that the procedure results in improved ultrasonographic status of the cervix and that the ultrasonographic cervical findings before and after surgery correlate with pregnancy outcome.

Adolescent↗

PubMed1994

A new method using vaginal ultrasound and transfundal pressure to evaluate the asymptomatic incompetent cervix.

OBJECTIVE: To evaluate the ability of ultrasound with transfundal pressure to detect the incompetent cervix in pregnant women at risk for this condition. METHODS: One hundred fifty pregnant women with no prior pregnancy losses were scanned transabdominally, and 31 asymptomatic pregnant women with a prior history of cervical incompetency or risk for this condition were scanned transvaginally. The control patients were scanned once between 16-24 weeks, and the patients at risk were studied 73 times between 8-25 weeks. After evaluating the cervix and its internal os, transfundal pressure was applied. Cervical cerclages were placed for cervical funneling and shortening in response to transfundal pressure or for a grossly incompetent cervix on ultrasound evaluation. RESULTS: Transfundal pressure elicited no changes in the internal cervical os of the 150 control patients, of whom 141 delivered at term, two miscarried at 22 and 23 weeks, and seven delivered prematurely (4.7%). Fourteen of the 31 pregnancies at risk for cervical incompetency revealed opening of the internal os or descent of the fetal membranes with transfundal pressure. Thirteen of these 14 pregnancies were treated with cerclage, with nine (64%) proceeding to term, three (21%) delivering prematurely, and two (14%) aborting. The one patient who did not receive a cerclage also aborted. In six cases, the cervix and its internal os appeared normal but the membranes protruded into the endocervical canal in response to transfundal pressure. CONCLUSION: Application of transfundal pressure during transvaginal ultrasound evaluation of the cervix and its internal os may assist in detecting the asymptomatic incompetent cervix.

Cervix Uteri↗

PubMed1993

Phenytoin and magnesium sulfate effects on fetal heart rate tracings assessed by computer analysis.

OBJECTIVE: To compare the effects of maternally administered phenytoin and magnesium sulfate on the fetal heart rate (FHR) using computer analysis. METHODS: Thirty-six nonlaboring preeclamptic women between 27-41 weeks' gestation were treated with either phenytoin or magnesium sulfate in a nonrandomized fashion. All fetuses were deemed to be well by traditional electronic-biophysical criteria. One-hour FHR recordings were analyzed by computer analysis before treatment. No other medications were administered. Tracings recorded 1 hour after drug administration were analyzed. Therapeutic serum levels were achieved in both groups before FHR tracings were reevaluated. Statistical analysis used paired Student t test, with significance set at P < or = .05. RESULTS: There were no differences in birth weight, gestational age, Apgar scores, or computer-analyzed FHR characteristics between the groups before treatment. Magnesium sulfate reduced significantly the frequency of accelerations of ten and 15 beats per minute; caused a 62% reduction in reactivity, defined as accelerations of 15 beats per minute in 20 minutes of FHR tracing (but no change in reactivity with accelerations of ten beats per minute); and reduced short- and long-term variability. Phenytoin reduced short-term variability only. CONCLUSION: Phenytoin does not confound the computer analysis of FHR tracings and may offer some advantage over magnesium sulfate when used for prophylaxis against eclampsia.

Diagnosis, Computer-Assisted↗

PubMed1985