Biomedical subjects

K St John

Publications and source records attributed to K St John.

7 recordsLinked to original sources

PubMed2001

Designing fast converging phylogenetic methods.

Absolute fast converging phylogenetic reconstruction methods are provably guaranteed to recover the true tree with high probability from sequences that grow only polynomially in the number of leaves, once the edge lengths are bounded arbitrarily from above and below. Only a few methods have been determined to be absolute fast converging; these have all been developed in just the last few years, and most are polynomial time. In this paper, we compare pre-existing fast converging methods as well as some new polynomial time methods that we have developed. Our study, based upon simulating evolution under a wide range of model conditions, establishes that our new methods outperform both neighbor joining and the previous fast converging methods, returning very accurate large trees, when these other methods do poorly.

Computational Biology↗

PubMed2001

Regulation of RpoS by a novel small RNA: the characterization of RprA.

Translational regulation of the stationary phase sigma factor RpoS is mediated by the formation of a double-stranded RNA stem-loop structure in the upstream region of the rpoS messenger RNA, occluding the translation initiation site. The interaction of the rpoS mRNA with a small RNA, DsrA, disrupts the double-strand pairing and allows high levels of translation initiation. We screened a multicopy library of Escherichia coli DNA fragments for novel activators of RpoS translation when DsrA is absent. Clones carrying rprA (RpoS regulator RNA) increased the translation of RpoS. The rprA gene encodes a 106 nucleotide regulatory RNA. As with DsrA, RprA is predicted to form three stem-loops and is highly conserved in Salmonella and Klebsiella species. Thus, at least two small RNAs, DsrA and RprA, participate in the positive regulation of RpoS translation. Unlike DsrA, RprA does not have an extensive region of complementarity to the RpoS leader, leaving its mechanism of action unclear. RprA is non-essential. Mutations in the gene interfere with the induction of RpoS after osmotic shock when DsrA is absent, demonstrating a physiological role for RprA. The existence of two very different small RNA regulators of RpoS translation suggests that such additional regulatory RNAs are likely to exist, both for regulation of RpoS and for regulation of other important cellular components.

Bacterial Proteins↗

PubMed2001

A prospective satisfaction study and cost analysis of a pilot child telepsychiatry service in Newfoundland.

We evaluated user satisfaction with a PC-based videoconferencing system used for child psychiatry assessments and performed a cost analysis. Thirty patients (aged 5-16 years), accompanied by a parent, completed a psychiatric assessment using the videoconferencing system. One of five child psychiatrists was randomly assigned to each assessment. Satisfaction questionnaires were completed after each assessment by the psychiatrist, patient and parent. Parents also completed a cost questionnaire. The telecommunications bandwidth was 336 kbit/s. The psychiatrists stated that they were either 'very satisfied' or 'satisfied' with the telepsychiatry assessments. On a five-point Likert scale (1 = lowest, 5 = highest), 28 of the 30 parents (93%) rated their satisfaction level as 5; the other two rated it 4. All 30 parents (100%) stated that they 'liked' the telepsychiatry assessment and would use the system again. Twenty-nine parents (97%) indicated that they would prefer to use the telepsychiatry system to travelling to see a child psychiatrist in person. Eleven children (aged 5-12) participated and all (100%) said they 'liked' using the telepsychiatry system. Five out of nine children (56%) stated they liked the 'television doctor' better than the 'real' doctor; four said they had no preference. Nineteen adolescents (aged 13-16 years) participated and most were very satisfied or satisfied with the system. Seventeen of the 19 adolescents (89%) said they would prefer to see the psychiatrist on the videoconferencing system to travelling for an assessment, and the same number said that they would use telepsychiatry again. The estimated total travel cost for the 30 patients was $12,849, an average of $428 per patient. The total cost of the telepsychiatry service for the three-month pilot was $12,575, or $419 per patient.

Adolescent↗

PubMed2000

A randomized, controlled trial of child psychiatric assessments conducted using videoconferencing.

We used a PC-based videoconferencing system to conduct child psychiatry assessments. The telecommunications link was six digital lines, giving a total bandwidth of 336 kbit/s. Twenty-three patients (aged 4-16 years), accompanied by their parents, completed two psychiatric assessments, one via videoconferencing and another face to face (FTF). The order of assessments was randomized. Questionnaires were used to record the diagnosis, treatment recommendations and the psychiatrists', patients' and their parents' satisfaction with each assessment. An independent evaluator concluded that in 22 cases (96%) the diagnosis and treatment recommendations made via the videoconferencing system were the same as those made FTF. The psychiatrists stated that videoconferencing assessments were an adequate alternative to FTF assessments and did not interfere with diagnosis. However, the responses from the psychiatrist satisfaction questionnaire showed that they preferred FTF assessments. No significant difference was found in the patients' or parents' satisfaction responses after the two types of assessment. The majority of children (82%) 'liked' using the telepsychiatry system and six (26%) preferred it to a FTF assessment. Most parents (91%) indicated that they would prefer to use the videoconferencing system than to travel a long distance to see a psychiatrist in person.

Adolescent↗

PubMed1994

Investigation of a pseudo-outbreak of orthopedic infections caused by Pseudomonas aeruginosa.

OBJECTIVE: To report a pseudoepidemic of Pseudomonas aeruginosa infections discovered during an investigation of postoperative joint infections. DESIGN: A retrospective review of case patients' hospital charts, operative reports, and laboratory data, as well as environmental culturing, polymerase chain reaction (PCR) ribotyping of outbreak isolates, and in vitro analysis of P aeruginosa growth characteristics. SETTING: A 510-bed, university-affiliated adult tertiary care hospital. RESULTS: Between October 1 and December 1, 1992, seven postsurgical joint infections were diagnosed, including four caused by P aeruginosa. A bottle of "sterile" saline used to process tissue specimens was found to be contaminated with P aeruginosa. Further investigation revealed that P aeruginosa had grown from seven additional tissue cultures, all of which had been processed with the contaminated saline. PCR ribotypes of the contaminant matched those of the clinical isolates. In vitro, P aeruginosa strains were viable in commercial nonbacteriostatic saline, but never caused visible turbidity. Six patients received antibiotics for their presumed infections; four patients had peripherally inserted central catheters placed, and one experienced severe anaphylactic reactions to several antibiotics. CONCLUSIONS: Pseudoepidemics due to common organisms are often difficult to detect, and delayed recognition can result in substantial morbidity. This outbreak investigation illustrates the potential for contamination of diluents in the microbiology laboratory and emphasizes the need for meticulous quality control.

Adolescent↗

PubMed1994

Comparison of anterior cervical fusions using autogenous bone graft obtained from the cervical vertebrae to the modified Smith-Robinson technique.

Anterior cervical discectomy and interbody grafting provide excellent results in treating cervical radiculopathy. This prospective study compares the results of the technique obtaining autogenous bone from the cervical vertebrae for grafting to the modified Smith-Robinson technique using autogenous iliac crest graft. Seven levels in six patients were fused using the vertebral body autograft technique and 43 levels in 40 patients using the standard technique. All patients had radiculopathy and neck pain. Statistically significant differences in fusion rate (4/7 vertebral body autograft; 40/43 modified Smith-Robinson) (p = 0.029), disc height maintenance (p = 0.001), and neck pain improvement (p = 0.05) occurred between the techniques. We do not recommend vertebral body autograft over the modified Smith-Robinson technique for anterior cervical fusion following discectomy.

Adult↗

PubMed1991

Adolescent and pre-adolescent suicide in Newfoundland and Labrador.

This study investigated suicides by people aged ten to 19 in Newfoundland and Labrador from 1977 to 1988. It is the first study of suicide in the province to use the records of death from all eight hospital pathology departments in the province and from the office of the Chief Forensic Pathologist. Cases were selected for the study using standardized criteria, independent of the manner of death recorded on the death certificate. A suicide rate of 4.37 per 100,000 was found. This rate and the age- and sex-specific suicide rates are lower than the official figures for Canada but higher than those reported in earlier Newfoundland studies. The rate for males was nearly five times the female rate, and the rate for people aged 15 to 19 was nearly six times that of people aged ten to 14. Suicide rates for Labrador were higher than for the island portion of the province for both Native and for non Native adolescents. Extremely high rates of suicide were found only among the Native population living in Northern Labrador, while none were recorded for Native people elsewhere. Firearms accounted for 54% and hanging for 33% of all suicides. Thirty percent of suicides occurred on a Saturday. Only 36 of the 63 deaths included in this study were designated as suicide on death certificates. The higher rate of under-reporting of suicide than in other jurisdictions suggests that official rates may not be useful for comparisons. The reasons for the high rate of under-reporting are discussed.

Adolescent↗