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Biomedical subjects

L Robertson

Publications and source records attributed to L Robertson.

At least 37 records · Page 2Linked to original sources
PubMed2000

Patch incorporation in diaphragmatic hernia.

BACKGROUND/PURPOSE: Biomaterial insertion often is required for closure of congenital diaphragmatic hernia (CDH). The optimal biomaterial remains uncertain. This study was designed to compare a commonly used patch (polytetrafluoroethylene) with a recently available fabric, fluorinated polyester. The aim of this study was to determine the clinical performance, histological tissue-polymer interaction, bacterial adhesion, and shrinkage rates of biomaterial inserted endoscopically into a CDH lamb model. METHODS: Polytetrafluoro-ethylene (PTFE) and fluorinated polyester (FP) were randomised for laparoscopic patch insertion into 12 lambs. All lambs (age <4 weeks) underwent 3-port laparoscopy, surgical creation of diaphragmatic hernia, and sutured patch placement. Two PTFE and 2 FP lambs were killed at 1-, 3-, and 6-month intervals postoperatively. Postmortem examination histopathology, electron microscopy, and specific bacterial broth immersion (Escherichia coil, Staphylococcus aurens, and epidermidis) were performed. RESULTS: All 12 lambs completed the study with intact patches that were fully peritonised. One abdominal adhesion was noted in a FP lamb at 6 months. FP was comparatively easier to insert, manipulate, and suture endoscopically. Histopathology findings showed that PTFE patches created a strong peripheral foreign body reaction with dystrophic calcification, whereas FP was well incorporated with intrapatch fibroblastic activity and neovascularsation. No significant difference in resistance to bacterial adhesion of relevant organisms was noted between the materials. Graft shrinkage for FP was 7% in one direction only, evident by 3 months. CONCLUSIONS: Fluorinated polyester has advantages in this laparoscopic lamb model. It shows rapid and sustained incorporation with intrapatch neovascularisation when compared with polytetrafluoro-ethylene's significant foreign body reaction. It was preferred for its endoscopic handling and suturing properties. The laparoscopic techniques used may contribute to the general lack of adhesions, and insufficient data are available to comment on the comparative effect of the materials on adhesion formation. No difference was demonstrated in resistance to bacterial adherence in the harvested materials.

Animals↗
PubMed2000

Cloning, expression and functional characterisation of a peroxiredoxin from the potato cyst nematode Globodera rostochiensis.

We report the cloning, expression and functional characterisation of a peroxidase belonging to the peroxiredoxin family from the potato cyst nematode Globodera rostochiensis, the first molecule of this type from any nematode parasitic on plants. The G. rostochiensis peroxiredoxin catalyses the breakdown of hydrogen peroxide, but not cumene or t-butyl hydroperoxide, in a trypanosomatid reducing system comprising trypanothione reductase, trypanothione and tryparedoxin. In common with its homologues from Onchocerca volvulus and Brugia malayi, the G. rostochiensis enzyme is present on the surface of invasive and post-infective juveniles despite the apparent lack of a cleavable N-terminal signal peptide. The possibility that the G. rostochiensis peroxiredoxin plays a role in protection of the parasite from plant defence responses is discussed.

Amino Acid Sequence↗
PubMed2000

Molecular characterization of the vanD gene cluster and a novel insertion element in a vancomycin-resistant enterococcus isolated in Canada.

A single vanD-containing Enterococcus faecium strain (N97-330) was isolated in Canada. The vanD-containing region was cloned and sequenced. Although the proteins have more than 96% identity to a previously described vanD region in BM4339, the vanS(D) gene contains a frameshift mutation that leads to a predicted truncated protein. Furthermore, sequence analysis of the ddl gene revealed the presence of an IS982-like element (ISEfm1) which interrupted the D-Ala-D-Ala ligase. This suggested the constitutive expression of the vanD operon, which was confirmed. Pulsed-field gel electrophoresis fingerprinting demonstrated that BM4339 was not related to N97-330 (>15 band differences). Both strains contained multiple copies of the IS982-like element.

Amino Acid Sequence↗
PubMed2000

Medical complications after stroke: a multicenter study.

BACKGROUND AND PURPOSE: This prospective, multicenter study was performed to determine the frequency of symptomatic complications up to 30 months after stroke using prespecified definitions of complications. METHODS: We recruited 311 consecutive stroke patients admitted to hospital. Research nurses reviewed their progress on a weekly basis until hospital discharge and again at 6, 18, and 30 months after stroke. RESULTS: Complications during hospital admission were recorded in 265 (85%) of stroke patients. Specific complications were as follows: neurological-recurrent stroke (9% of patients), epileptic seizure (3%); infections-urinary tract infection (24%), chest infection (22%), others (19%); mobility related-falls (25%), falls with serious injury (5%), pressure sores (21%); thromboembolism-deep venous thrombosis (2%), pulmonary embolism (1%); pain-shoulder pain (9%), other pain (34%); and psychological-depression (16%), anxiety (14%), emotionalism (12%), and confusion (56%). During follow-up, infections, falls, "blackouts, " pain, and symptoms of depression and anxiety remained common. Complications were observed across all 3 hospital sites, and their frequency was related to patient dependency and duration after stroke. CONCLUSIONS: Our prospective cohort study has confirmed that poststroke complications, particularly infections and falls, are common. However, we have also identified complications relating to pain and cognitive or affective symptoms that are potentially preventable and may previously have been underestimated.

Accidental Falls↗
PubMed2000

Evaluating the financial impact of clinical trials in oncology: results from a pilot study from the Association of American Cancer Institutes/Northwestern University clinical trials costs and charges project.

PURPOSE: Medical care for clinical trials is often not reimbursed by insurers, primarily because of concern that medical care as part of clinical trials is expensive and not part of standard medical practice. In June 2000, President Clinton ordered Medicare to reimburse for medical care expenses incurred as part of cancer clinical trials, although many private insurers are concerned about the expense of this effort. To inform this policy debate, the costs and charges of care for patients on clinical trials are being evaluated. In this Association of American Cancer Institutes (AACI) Clinical Trials Costs and Charges pilot study, we describe the results and operational considerations of one of the first completed multisite economic analyses of clinical trials. METHODS: Our pilot effort included assessment of total direct medical charges for 6 months of care for 35 case patients who received care on phase II clinical trials and for 35 matched controls (based on age, sex, disease, stage, and treatment period) at five AACI member cancer centers. Charge data were obtained for hospital and ancillary services from automated claims files at individual study institutions. The analyses were based on the perspective of a third-party payer. RESULTS: The mean age of the phase II clinical trial patients was 58.3 years versus 57.3 years for control patients. The study population included persons with cancer of the breast (n = 24), lung (n = 18), colon (n = 16), prostate (n = 4), and lymphoma (n = 8). The ratio of male-to-female patients was 3:4, with greater than 75% of patients having stage III to IV disease. Total mean charges for treatment from the time of study enrollment through 6 months were similar: $57,542 for clinical trial patients and $63,721 for control patients (1998 US$; P =.4) CONCLUSION: Multisite economic analyses of oncology clinical trials are in progress. Strategies that are not likely to overburden data managers and clinicians are possible to devise. However, these studies require careful planning and coordination among cancer center directors, finance department personnel, economists, and health services researchers.

Aged↗
PubMed2000

Dental nerve blocks. Toothache remedies for the acute-care setting.

Ideally, tooth pain is managed by a competent dentist, who can provide definitive care. However, timely access to such care may not be available late at night, on weekends, or in rural practice settings. This article introduces primary care physicians to dental nerve blocks that can be learned without extensive training and use in the acute-care setting to provide temporary relief of oral, dental, and facial pain.

Humans↗
PubMed2000

Identification of perivitelline N-linked glycans as mediators of sperm-egg interaction in chickens.

This study demonstrates that carbohydrates play an essential role in sperm-egg interactions in birds. Sperm-egg interaction was measured in vitro as the ability of spermatozoa to hydrolyse a small hole in the inner perivitelline layer, the equivalent of the mammalian zona pellucida. Preincubation with Triticum vulgaris lectin (WGA) and succinyl-WGA (S-WGA) at 10 microgram ml(-1) resulted in complete inhibition of sperm-egg interaction, whereas at the same concentration a range of other lectins (Canavalia ensiformis (Con A), Arachis hypogea (PNA), Ulex europaeus II (UEA II), Solanum tuberosum (STA), Tetragonolobus purpureas (LTA) and Pisum sativum (PSA)) were unable to inhibit sperm egg interaction significantly, although fluorescein-labelled derivatives of these lectins were found to stain the inner perivitelline layer. Significant inhibition of sperm-egg interaction was achieved by the addition of N-acetyl-D-glucosamine and fucoidin to the assay mixture; however, D-glucose, D-galactose, D-fucose and L-fucose had no significant effect on sperm-egg interaction. Pretreatment of the inner perivitelline layer with N-glycanase significantly reduced sperm-egg interaction, whereas treatment with O-glycanase had no effect. These results demonstrate that N-linked glycans play an essential role in sperm-egg interaction in chickens.

Acetylglucosamine↗
PubMed2000

Formation of a secondary corpus luteum after ultrasound-guided follicular aspiration in cows.

This paper reports the observed formation of a secondary corpus luteum (CL) in the presence of the cyclic corpus luteum, on the ovaries of a cow after ultrasound-guided follicular aspiration for oocyte recovery. The secondary structure, although smaller and lighter (4.97 g vs. 6.02 g) than the natural one, had the typical macroscopic appearance of a corpus luteum. Histological examination of the structure using electron microscopy revealed typical structural features of a natural CL. Mean tissue progesterone concentration was significantly lower in the secondary CL (31.15 +/- 3.11 compared with 58.29 +/- 6.32 micrograms/g tissue of the cyclic CL) and oestradiol-17 beta significantly higher than in the natural CL (108 +/- 11.6 compared with 74.2 +/- 7.81 pg/g tissue). P450scc and P450(17 alpha) mRNA was detected in both structures while P450arom and full-length mRNA FSH receptor were detected only in the secondary structure.

Animals↗
PubMed1999

Plasma estradiol FSH and LH concentration after dominant follicle aspiration in the cow.

This work investigates the estrogenic role of the dominant follicle with regard to regulation of plasma FSH and LH concentration. Eight Holstein-Friesian cows were used for aspiration of the dominant follicle using ultrasound guidance during the early, mid and late stages of the luteal phase. Blood samples were collected at 15-min intervals from 4 h before until 7 h after aspiration. Plasma progesterone concentration increased from 0.7 to 7.2 ng mL-1 from early to mid luteal phase and then fell slightly to 5.9 ng mL-1 in the late luteal phase, but remained unaffected by follicle puncture. The follicular aspirate contained a thousandfold higher estradiol, than plasma concentration but its estradiol:progesterone ratio remained at around 2 at each stage of the luteal phase. Aspiration caused plasma estradiol concentration to fall from 1.4 to 0.7, 1.8 to 1.0 and 1.7 to 0.8 pg mL-1 in the early, mid and late stages of the luteal phase, respectively (P < 0.05). At the same time, mean plasma FSH concentration was increased from 1.1 to 1.8, 1.7 to 2.9 and 0.8 to 1.9 ng mL-1 (P < 0.05), respectively. The results suggest that estradiol secreted from dominant follicles selectively regulates gonadotropin secretion, since aspiration of the dominant follicle at any stage of the cycle affected circulating FSH but did not appear to influence the mean LH concentration.

Animals↗
PubMed1999

Is there an increased clinical severity of patients with eating disorders under managed care?

OBJECTIVES: We sought to examine possible differences in medical status at presentation in 1996, compared to 1991, of adolescents with eating disorders (EDs) at a hospital-based multidisciplinary care program to reflect the increasing market penetration of managed care. DESIGN: Charts were reviewed for all new patients scheduled in a hospital-based outpatient ED program in 1996 and 1991. The 92-item standardized data extraction form included information on demographics, indicators of illness severity at the first visit, and subsequent hospitalization. The need for primary care referral was verified using billing records. Data were analyzed with Student's t-test, Chi-square, Fisher's exact, and Mann-Whitney U tests using SPSS 7.5. RESULTS: Of the 153 total patients, 133 kept their intake appointment and 130 (98%) of these had charts available for review. The age, racial/ethnic characteristics, and average length of disordered eating behaviors were not significantly different over the 5-year period. Referral from a primary care clinician was more commonly required in 1996 than 1991 (59% vs. 11%; p < .0001). Eighteen percent of the patients seen in 1996 were admitted from the initial appointment for medical stabilization, compared to 1.5% in 1991 (p = .002). Comparing 1996 to 1991, a similar number of patients had symptoms consistent with anorexia nervosa, whereas fewer patients in 1996 gave a history of bingeing and purging (22% vs. 40%; p = .027). There were no significant differences in indicators of illness severity, treatment by primary care clinician prior to referral, or hospitalization rates for those patients with and without managed care. CONCLUSIONS: Patients in 1996 were more likely to require referrals, were less likely to have symptoms consistent with bulimia nervosa, and were more likely to be admitted for medical stabilization. There were no differences in patient presentation characteristics or initial hospitalization rates based on their managed care status. Further research is needed to investigate the changes in illness severity at presentation and to assess the role that managed care plays in the treatment of patients with eating disorders.

Adolescent↗
PubMed1999

Direct analysis of the secretions of the potato cyst nematode Globodera rostochiensis.

Secretions were induced from second (invasive) stage juveniles (J2s) of the potato cyst nematode Globodera rostochiensis by exposing them to 5-methoxy-N,N-dimethyl tryptamine oxalate (DMT). Secretions were collected from J2s in sufficient quantity to allow direct analysis. Gel electrophoresis followed by monochromatic silver staining demonstrated the presence of at least 10 proteins. The presence of several enzymes, including superoxide dismutase and proteases, was demonstrated using Western blots and activity assays. Antisera raised against the secretions recognized bands on Western blots consistent in molecular mass with those identified on silver stained gels. The antisera recognized structures implicated in the production of secretions including the subventral gland cells and surface of J2s.

Animals↗
PubMed1998

Infections in patients with chronic lymphocytic leukemia treated with fludarabine.

BACKGROUND: Fludarabine, a purine analogue with activity in chronic lymphocytic leukemia, is usually well tolerated. Although serious infections after fludarabine therapy have been described, a systematic analysis of the risk factors for such infections in chronic lymphocytic leukemia is lacking. OBJECTIVE: To determine the risk factors for major infection in patients with chronic lymphocytic leukemia treated with fludarabine. DESIGN: Retrospective review of medical records. SETTING: Cancer center. PATIENTS: 402 patients with chronic lymphocytic leukemia not previously treated or treated with chlorambucil (with or without prednisone) who received fludarabine (30 mg/m2 of body surface area per day for 5 days) with or without prednisone at 4-week intervals. RESULTS: Infections occurred more often in previously treated (144 of 248 [58%]) than in previously untreated (53 of 154 [34%]) patients (P < 0.001). Listeriosis or pneumocystosis occurred in 12 of 170 (7%) previously treated patients receiving fludarabine plus prednisone, 0 of 78 previously treated patients receiving fludarabine alone, and 2 of 154 (1%) previously untreated patients receiving fludarabine plus prednisone (P = 0.003). Univariate analysis identified previous chemotherapy, advanced disease, failure to respond to fludarabine, elevated serum beta2-microglobulin level (P < 0.001), low serum albumin level (P = 0.024), elevated serum creatinine concentration (P = 0.008), and low granulocyte count (P = 0.003) as risk factors for infection. Multivariate analysis identified Rai stage III or IV (odds ratio, 1.98 [95% CI, 1.17 to 3.94]), previous treatment (odds ratio, 2.24 [CI, 1.43 to 3.51]), and elevated serum creatinine concentration (odds ratio, 1.98 [CI, 1.09 to 3.67]) as statistically significant independent risk factors for major infection. A baseline granulocyte count of more than 1000 cells/microL was protective (odds ratio, 0.54 [CI, 0.29 to 0.99]). Five (26%) of 19 patients with a CD4 count less than 50 cells/mL developed cutaneous zoster compared with 9 (6%) of 139 patients with a CD4 count greater than 50 cells/mL (P = 0.01). CONCLUSIONS: Fludarabine used in previously treated patients with chronic lymphocytic leukemia may be associated with infections involving T-cell dysfunction, such as listeriosis, pneumocystosis, mycobacterial infections, and opportunistic fungal and viral infections. Prophylaxis or presumptive therapy should be initiated in the appropriate setting.

Analysis of Variance↗
PubMed1998

Electrophysiological evidence against a neurotransmitter role of corticotropin-releasing hormone (CRH) in primary somatosensory cortex.

The possible neurotransmitter role of corticotropin-releasing hormone (CRH) was studied in the primary somatosensory cortex of the rat. Electrical activity of single neurones was recorded in layers II-VI of cortex, and in the region of the locus coeruleus. Iontophoresis and pressure ejection were employed to locally apply CRH, and changes in spontaneous, synaptically driven and iontophoretically driven firing were examined. In the cortex, of 62 neurones recorded most (51) were completely unaffected by high and prolonged current/pressure ejections of CRH. Depression of firing was occasionally seen (8 of 62), while a very few (3) were weakly excited. Of 25 cells studied with vibrissal stimulation to evoke excitatory synaptic responses, responses in two cells were depressed and in two they were enhanced. Activity that was evoked by iontophoretic ejection of excitatory amino acids, such as glutamate, was depressed in 6 of 40 cells (none were enhanced). Such effects as were seen were weak and often difficult to reproduce. The effect of CRH on depressions produced by GABA was also tested in four experiments. No effects on the amplitude or duration of the depressions were observed. In contrast recordings made in the midbrain, in the region of the locus coeruleus, resulted in over half the neurones (11 of 20) showing clear reproducible excitatory responses to CRH applications. Solutions used in the experiments were analysed using chromatography, radioimmunoassay and bioassay, and no significant degradation of the peptide was found compared with the synthetic standard (CRH (1-41)). The data provide evidence against CRH acting as a neurotransmitter or modulator in primary cortex, suggesting that the CRH which is localized in certain types of cortical cells is involved in other processes.

Animals↗
PubMed1998

Quantitative coronary angiographic and intravascular ultrasound assessment of a new nonarticulated stent: report from the Advanced Cardiovascular Systems MultiLink stent pilot study.

OBJECTIVES: The purpose of this study was to evaluate the safety, feasibility, optimal deployment technique and 1-year clinical outcome for the Advanced Cardiovascular Systems (ACS) MultiLink stent. BACKGROUND: Optimal stent deployment assessed by quantitative coronary angiography and intravascular ultrasound (IVUS) is associated with improved clinical outcome. METHODS: Forty-nine consecutive patients with a discrete stenosis in a native coronary artery 3 to 4 mm in diameter were treated with the new, balloon-expandable ACS MultiLink stent. Stent expansion was assessed in all patients using quantitative coronary angiography and serial IVUS imaging after 8-, 12- and 16-atm inflations. Clinical follow-up was obtained at 30 days and 1 year. RESULTS: All 49 patients had successful placement of a MultiLink stent without death, emergency coronary artery bypass graft surgery or Q wave myocardial infarction. After placement of the MultiLink stent, the minimal lumen diameter increased from 1.24 to 2.98 mm (p < 0.001), and diameter stenosis decreased from 61% to 7% (p = 0.001). Minimal lumen cross-sectional area by IVUS increased progressively after 8, 12 and 16 atm (5.6 to 6.8 to 7.4 mm2, respectively, p < 0.001). However, only 64% of stents achieved a lumen/reference area ratio > or = 70%. No adverse clinical events occurred by 30 days, and by 1 year only one patient (2.0%) required revascularization of the stented artery. CONCLUSIONS: Treatment of stenoses in native coronary arteries with the MultiLink stent is associated with a high success rate and a low incidence of adverse events by 1 year, despite the fact that the majority of stents did not meet IVUS-defined criteria for "optimal stenting" derived from first-generation devices.

Aged↗
PubMed1998

Dihydropyrimidine dehydrogenase pharmacogenetics in Caucasian subjects.

AIMS: Dihydropyrimidine dehydrogenase (DPD) catalyses the reduction of pyrimidines, including the anticancer agent 5-fluorouracil (5FU). Impaired 5FU degradation, through low DPD activity, has led to severe, life-threatening or fatal toxicity after administration of 5FU. Complete DPD deficiency is associated with the inherited metabolic disease thymine uraciluria. Several mutations in the gene encoding DPD have recently been identified, but the phenotype-genotype concordance of these alterations in the general population has not been reported. METHODS: Mononuclear cells were isolated from whole blood and DPD activity was determined after ex vivo incubation with 14C-5FU followed by h.p.1.c. analysis of 5FU metabolites. Analysis of mutations in the DPD gene at an exon splice site, codons 534, 543, and 732, and a deletion at base 1897 (deltaC1897) were performed in 30 subjects with the lowest and 30 subjects with the highest enzyme activity using PCR-RFLP. RESULTS: DPD activity was measured in 226 Caucasian subjects and was highly variable (range 19.1-401.4 pmol min(-1)mg(-1) protein). Mutations were frequently observed at codons 543 (allele frequency 28%), 732 (allele frequency 5.8%), and 534 (allele frequency 0.8%), but were not associated with low DPD activity. There were no splice site or deltaC1897 mutations found in this population. CONCLUSIONS: The five mutations analysed in this study are insufficient for identification of patients at risk for 5FU toxicity or thymine uraciluria. Both the splice site mutation and deltaC1897 are relatively rare in the general Caucasian population. Therefore, identification of further molecular alterations is required to facilitate the use of DPD analysis in genetic diagnosis and cancer therapeutics.

Alleles↗
PubMed1998

Peri-operative dysrhythmias in patients undergoing major vascular surgery--a preliminary report.

The objective of this prospective study was to determine the nocturnal/diurnal distribution of peri-operative cardiac dysrhythmias in patients with coronary artery disease undergoing major vascular surgery. Eight patients with significant coronary artery disease undergoing major vascular surgery were studied. Continuous Holter monitoring was performed on each patient from approximately 1 h pre-operatively until 2-5 days post-operatively. Frequencies of isolated supraventricular and ventricular premature beats, and runs of supraventricular and ventricular premature beats were calculated for 6-h periods (00.00-06.00; 06.00-12.00; 12.00-18.00; 18.00-24.00 hours). Supraventricular tachycardia occurred significantly more frequently between 00.00 and 06.00 hours than during the other 6-h periods studied in the post-operative period following major vascular surgery.

Aged↗
PubMed1998

Increased nuclear traffic chaos in hyphae of Aspergillus nidulans: molecular characterization of apsB and in vivo observation of nuclear behaviour.

Filamentous fungi are model microorganisms for studying nuclear migration in eukaryotic cells. Two genes, apsA and apsB (=anucleate primary sterigmata), were identified in Aspergillus nidulans that affect nuclear distribution in hyphae and specifically block conidiophore development at the metula stage when mutant. Here we describe the cloning, sequencing and molecular analysis of apsB. The gene encodes a 121 kDa coiled-coil, hydrophilic protein that was localized in the cytoplasm. No protein-protein interaction was detected between ApsB and ApsA, a membrane-associated, previously identified protein. An apsB null mutant was characterized by video epifluorescence microscopy using strains that express green fluorescent protein (GFP) in nuclei. With this novel approach, we have discovered a new mutant phenotype and have found that nuclei display an increased chaotic movement in older hyphal compartments that results in clustering and an uneven distribution of these organelles. These results suggest a regulatory role of ApsB in nuclear migration.

Amino Acid Sequence↗