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Biomedical subjects

S Walker

Publications and source records attributed to S Walker.

At least 217 records · Page 12Linked to original sources
PubMed1995

The bovine herpesvirus alpha gene trans-inducing factor activates transcription by mechanisms different from those of its herpes simplex virus type 1 counterpart VP16.

In herpes simplex virus (HSV)-infected cells, viral gene expression is initiated when the immediate-early, or alpha, genes are transactivated by the alpha gene trans-inducing factor (alpha TIF), a component of the infecting virion. The protein binds to one or more recognition elements (TAATGARAT) in the promoters of alpha genes via interaction with the cellular proteins Oct-1 and CFF. The alpha TIF of HSV (HSV-alpha TIF) is believed to subsequently accelerate the assembly of the transcription complex by direct contact between its carboxyl-terminal acidic activation domain and at least two components of the transcription apparatus, TAFII40 and TFIIB. Like its HSV counterpart, the alpha TIF of bovine herpesvirus (BHV) (designated BHV-alpha TIF) also transactivates alpha gene promoters and for full activity exhibits a requirement for its extended carboxyl-terminal region. Despite this requirement, there is a notable lack of homology to the carboxyl-terminal acidic activation domain of HSV-alpha TIF. We swapped the amino- and carboxyl-terminal domains of HSV-alpha TIF and BHV-alpha TIF to make chimeric proteins. Using these chimeras, we show that the carboxyl terminus of BHV-alpha TIF is insufficient for transactivation, which requires cooperative determinants in both the amino-terminal and carboxyl-terminal regions of the protein. We have previously shown that the amino-terminal determinant in BHV-alpha TIF displays reduced but significant independent transactivation potential. Interestingly, this amino-terminal determinant appears not to reside in the HSV-alpha TIF, which displays no independent amino-terminal activity. Furthermore, we show that the amino-terminal activation domain of BHV-alpha TIF may be able to act synergistically with the carboxyl-terminal activation domain of HSV-alpha TIF, since a chimeric protein containing both domains appeared to be more efficient at activating transcription than either alpha TIF. In addition, the amino terminus of HSV-alpha TIF could not restore activity when linked to the carboxyl terminus of BHV-alpha TIF, while the amino terminus of BHV-alpha TIF reconstituted an intact protein with potent activation potential. We also show that in fusions with the DNA binding domain of GAL4, full activity requires the entire BHV-alpha TIF, although both amino and carboxyl termini display some activity on their own. In contrast, for HSV-alpha TIF, the carboxyl terminus is sufficient and possibly even more potent than the entire protein, while the amino-terminus is devoid of activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1995

Postoperative vomiting in children.

A survey of the incidence of postoperative vomiting in 1476 children was conducted over a two-month period as part of our quality assurance programme. The incidence of vomiting was 24%, and was highest in children over three years of age and in those receiving opioids. The incidence is lower than that recorded in an earlier (1981) survey in our hospital. Changes in anaesthetic practices may have contributed to this decrease.

Adenoidectomy↗
PubMed1995

Facial identity and facial speech processing: familiar faces and voices in the McGurk effect.

An experiment was conducted to investigate the claims made by Bruce and Young (1986) for the independence of facial identity and facial speech processing. A well-reported phenomenon in audio-visual speech perception--the McGurk effect (McGurk & MacDonald, 1976), in which synchronous but conflicting auditory and visual phonetic information is presented to subjects--was utilized as a dynamic facial speech processing task. An element of facial identity processing was introduced into this task by manipulating the faces used for the creation of the McGurk-effect stimuli such that (1) they were familiar to some subjects and unfamiliar to others, and (2) the faces and voices used were either congruent (from the same person) or incongruent (from different people). A comparison was made between the different subject groups in their susceptibility to the McGurk illusion, and the results show that when the faces and voices are incongruent, subjects who are familiar with the faces are less susceptible to McGurk effects than those who are unfamiliar with the faces. The results suggest that facial identity and facial speech processing are not entirely independent, and these findings are discussed in relation to Bruce and Young's (1986) functional model of face recognition.

Adult↗
PubMed1995

Student performance appraisal: an approach to evaluation of attitudes in medical laboratory technology students.

This paper describes the development and implementation of a new evaluation format for assessing professional attitudes in medical laboratory technology students--the performance appraisal. This tool measures attitudes considered desirable in the ¿ideal technologist¿, and links the presence or absence of these attitudes to behaviors which can be observed in the student. The performance appraisal functions not only as an evaluation instrument for instructors, but as a learning tool for students, who can identify behavioral objectives, assess their own progress, and set goals and strategies for development of professional attitudes. Details regarding the administration of the evaluation instrument, such as rating scales, remedial planning, and responsibilities of faculty, clinical coordinators, and students are presented. In addition, controversies regarding the evaluation of professional attitudes are discussed, including: optimizing instructor objectivity; timing and grading of evaluations; forwarding of evaluations from one instructor to another; identification of mandatory and desirable attitudes; and criterion referencing of objectives. Plans for future development of the system are included.

Attitude of Health Personnel↗
PubMed1995

Tourist health services at tropical island resorts.

An unfamiliar holiday environment may give rise to a range of common and unique medical conditions and injuries. Based on a six-month retrospective analysis of clinic records, the present study reports a detailed profile of health services provided for guests at three tropical island tourist resorts. A total of 1183 clinic visits were analysed; 735 (62 per cent) concerned medical conditions, while 448 (38 per cent) were related to injuries. The most common medical conditions treated were respiratory, digestive, skin problems, eye disorders, and genito-urinary complaints. Injuries included lacerations, bites and stings, sprains and fractures. Health services consisted mainly of medication, specialist nursing care and first aid. Study findings highlight the advantages of using an internationally accepted classification system for primary health research, and the critical role of the nurse in tourist health services.

Australia↗
PubMed1994

Site-specific conformational alteration of the Oct-1 POU domain-DNA complex as the basis for differential recognition by Vmw65 (VP16).

We show that the presence of a regulatory cis-acting element that flanks the core octamer site and dictates selectivity in the response to Vmw65 (VP16), while dispensable for POU binding per se, induces a conformational alteration in the nature of the POU domain in the DNA complex. A single substitution in the flanking signal distorts the POU complex and without affecting overall POU binding prevents Vmw65 interaction. Alternatively, substitution of a residue in the homeodomain predicted to contact the GARAT region prevents its recognition even on a wild-type motif, causing a reversion to the DNA binding pattern seen on a cellular motif and at the same time inefficient recognition by Vmw65. The results indicate that Vmw65 recognizes a particular POU domain conformation induced by the presence of the flanking GARAT region.

Base Sequence↗
PubMed1994

Higher order self-assembly of vesicles by site-specific binding.

The association of lipid molecules into spherical vesicles in solution as a result of non-specific intermolecular forces constitutes a primary self-assembly process. Such vesicles can undergo a secondary self-assembly into higher order structures in a controlled and reversible manner by means of site-specific ligand-receptor (biotin-streptavidin) coupling. Cryoelectron microscopy shows these structures to be composed of tethered, rather than adhering, vesicles in their original, unstressed state. In contrast, vesicles aggregated by nonspecific, such as van der Waals, forces are deformed and stressed, producing unstable structures. Vesicle association by site-specific binding provides a practical mechanism for the production of stable, yet controllable, microstructured biomaterials.

Adhesiveness↗
PubMed1994

Effect of ursodeoxycholic acid on liver and bile duct disease in primary sclerosing cholangitis. A 3-year pilot study with a placebo-controlled study period.

Primary sclerosing cholangitis is a cholestatic disease of the liver characterized by progressive fibrotic inflammation and obliteration of the extra- and/or intrahepatic bile ducts. There is no effective therapy. We, therefore, studied the safety and efficacy of ursodeoxycholic acid in patients with primary sclerosing cholangitis with or without additional ulcerative colitis. In a 1-year ursodeoxycholic acid treatment period, which preceded the controlled study period, ursodeoxycholic acid was well tolerated in 22 of 24 patients with ulcerative colitis and in all three patients without ulcerative colitis. In two patients with ulcerative colitis the dose of 750 mg ursodeoxycholic acid/day led to diarrhea, but following reduction of the dose to 500 and 250 mg/day ursodeoxycholic acid was well tolerated. After 1 year of ursodeoxycholic acid treatment, 20 patients were randomly assigned to receive either ursodeoxycholic acid 750 mg/day or placebo. All of them finished a double-blind, placebo-controlled study period. During ursodeoxycholic acid treatment, the liver enzymes improved markedly. The difference in alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and gamma-glutamyltransferase between the placebo and ursodeoxycholic acid group was significant (p < 0.05). Following ursodeoxycholic acid treatment, pruritus and fatigue improved in half of the patients but the difference between the placebo and ursodeoxycholic acid group was not significant. According to the ethical guidelines, after 3 months of placebo treatment, the controlled study had to be discontinued because of a more than twofold increase of serum transaminases in 8/10 patients on placebo. After the end of the controlled study, all patients were continuously treated with ursodeoxycholic acid for up to 4 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Omeprazole-induced increase in the absorption of bismuth from tripotassium dicitrato bismuthate.

OBJECTIVE: Omeprazole is an effective drug for treating active peptic ulcer, whereas tripotassium dicitrato bismuthate can prevent ulcer relapse if Helicobacter pylori is eradicated. Because both drugs will be given concomitantly, drug interactions have to be considered, especially since absorption of bismuth may be dependent on intragastric pH, which will be elevated by omeprazole. METHODS: In a placebo-controlled crossover study, six healthy volunteers received daily oral doses of 40 mg omeprazole for 1 week and a single oral dose of 240 mg tripotassium dicitrato bismuthate. Plasma concentration-time profiles (AUC) and urinary excretion (Ae) of bismuth were measured by atomic absorption spectrophotometry and plasma levels of omeprazole by HPLC. In addition, intragastric pH values were monitored for 8 hours. RESULTS: As expected, control mean pH values (2.1) were evaluated to 4.7 by omeprazole (p = 0.001), which was eliminated with a half-life of 1.3 +/- 0.7 hours (mean +/- SD) and an oral clearance of 387 +/- 221 ml/min. The increase of intragastric pH was related to the AUC of omeprazole (r = 0.89; p = 0.017). Omeprazole increased absorption of bismuth because AUC and Ae were higher (p < or = 0.05) during omeprazole treatment (172 +/- 158 micrograms/L.hr and 1.9 +/- 2.0 mg/8 hr, respectively) compared with placebo (46 +/- 33 micrograms/L.hr and 0.27 +/- 0.28 mg/8 hr, respectively). A significant correlation (r = 0.85; p = 0.038) could be observed between intragastric pH differences and Ae values. CONCLUSIONS: Omeprazole caused an increase of the systemic availability of bismuth from tripotassium dicitrato bismuthate. Whether this pharmacokinetic interaction between both drugs results in alterations of H. pylori eradication or the toxic potential of bismuth remains to be elucidated by further clinical studies.

Administration, Oral↗
PubMed1994

Active pulmonary tuberculosis in patients with AIDS: spectrum of radiographic findings (including a normal appearance).

PURPOSE: To assess the efficacy of chest radiography in the detection of active pulmonary tuberculosis in patients with acquired immunodeficiency syndrome (AIDS). MATERIALS AND METHODS: Initial interpretations of chest radiographs of 133 adult patients with AIDS and positive sputum or bronchoalveolar lavage cultures for Mycobacterium tuberculosis were reviewed. Radiographic findings were correlated with CD4 T-cell counts, sputum stains for acid-fast bacilli (AFB), and antituberculous drug sensitivity. RESULTS: Forty-eight (36%) patients had a primary M tuberculosis pattern, 38 (28%) had a postprimary M tuberculosis pattern, 19 (14%) had normal radiographs, 17 (13%) had atypical infiltrates, seven (5%) had minimal radiographic changes, and four (3%) had a miliary pattern. Normal chest radiographs were seen for 10 (21%) of 48 patients with less than 200 T cells per microliter and one (5%) of 20 patients with more than 200 T cells per microliter. Drug sensitivity and sputum staining for AFB did not correlate with radiographic findings. Overall, 19% of cases had multidrug resistance to antituberculous medications. CONCLUSION: Chest radiographs did not suggest active tuberculosis in 43 (32%) of 133 AIDS patients with active pulmonary tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMed1994

Parent-rating and self-report measures in the psychiatric assessment of adolescents.

Thirty adolescents who received a psychiatric diagnosis based on the DSM-III clinical criteria were compared to 28 adolescents who were free of a diagnosis using the same criteria, on a parent-completed questionnaire (Revised Behavior Problem Checklist) and self-report measures (Revised Children's Manifest Anxiety Scale, Children's Depression Inventory, SCL-90-R). The two groups of adolescents were significantly distinguished by scores from the parent questionnaire but not by self-report measures. Possible explanations for the discrepant results are discussed. It is concluded that the parent measure may be used to reliably distinguish adolescents with psychiatric disorders from those free of similar disorders.

Adolescent↗
PubMed1994

Failed back surgery syndrome.

Patient selection for repeated spinal surgery is not uniform and must be further refined. A multidisciplinary approach with careful evaluation of physical, psychological and environmental factors is ideal. Improved imaging should delineate disorders more clearly, and advances in surgical technique may improve outcome. It is likely, however, that a number of patients will continue to require long-term pain management.

Humans↗
PubMed1994

Proliferative activity and aneuploidy in pleomorphic adenomas of the salivary glands.

We used flow cytometry in a retrospective study of pleomorphic adenoma and carcinoma arising in pleomorphic adenoma, using paraffin-embedded tissue, to assess the relationship among proliferative activity, ploidy, and recurrence or malignant transformation. Twenty-four specimens obtained from 22 tumors were acceptable for analysis (co-efficient of variation, < or = 7.0), including multiple samples from two tumors. Fourteen tumors (13 benign and one malignant) were diploid. Six tumors were aneuploid: four benign pleomorphic adenomas and two carcinomas arising in pleomorphic adenoma. Two tetraploid tumors were malignant recurrences from the same patient. Of the recurrent tumors (nine benign and four malignant), 54% were aneuploid. The highest S-phase fractions were observed in recurrent and malignant pleomorphic adenomas. Immunostaining with p105, a nuclear proliferation antigen, revealed increased proliferative activity in a majority of pleomorphic adenomas. Increased proliferative activity and aneuploidy occurred in benign pleomorphic adenomas.

Adenoma, Pleomorphic↗