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Biomedical subjects

M Campbell

Publications and source records attributed to M Campbell.

At least 181 records · Page 10Linked to original sources
PubMed1999

Exposure of health care workers to pentamidine isethionate.

Pentamidine isethionate is currently used for the prophylaxis and treatment of Pneumocystis carinii pneumonia. Its use has been associated with a number of symptoms in staff administering treatment, and there are some additional concerns about possible adverse health effects of long term exposure. The aim of this study was to quantify exposure of health care staff administering nebulized pentamidine to patients. Personal breathing zone and static air samples at the height of the patient's head were collected during the nebulization of pentamidine to nine sequential outpatients attending a haemophilia unit. These were analysed using a standard method allowing the exposure of staff to be estimated. The duration of treatment varied between 15 and 60 min. Personal breathing zone samples showed exposure to be between 2 and 100 micrograms/m3. Static samples showed the concentration of pentamidine in the room varied from 15 to 2,100 micrograms/m3. While these exposures were relatively low, they were higher than some other studies have reported, and may pose some risk of adverse effects to staff. Some simple measures could reduce staff exposure.

Aerosols↗
PubMed1999

Antipsychotics in children and adolescents.

OBJECTIVES: To present a critical overview of the available evidence for the efficacy and safety of antipsychotic agents in children and adolescents and to identify knowledge gaps and needs for further research. Data from adults that are relevant to children are discussed. METHOD: Mainly reports of double-blind, placebo-controlled studies were reviewed. RESULTS: In children and adolescents, antipsychotics are used to treat psychotic and a variety of nonpsychotic conditions. The amount of data based on well-designed, double-blind, placebo-controlled studies with satisfactory sample sizes in diagnostically homogeneous subjects is modest. CONCLUSIONS: Currently available standard antipsychotics have a definite role in the treatment of children and adolescents. The use of these agents is limited mainly by tardive and withdrawal dyskinesias and, in some patients, by excessive sedation. The atypical antipsychotics should be critically assessed and compared with psychosocial interventions; if effective, the combination of both types of treatments should be evaluated.

Adolescent↗
PubMed1999

Comparison of isolation media for recovery of Burkholderia cepacia complex from respiratory secretions of patients with cystic fibrosis.

Burkholderia cepacia selective agar (BCSA) has previously been devised for isolation of B. cepacia from respiratory secretions of patients with cystic fibrosis and tested under research laboratory conditions. Here we describe a study in which BCSA, oxidation-fermentation polymyxin bacitracin lactose agar (OFPBL), and Pseudomonas cepacia agar (PCA) were compared in routine culture procedures for the ability to grow B. cepacia and inhibit other organisms. Three hundred twenty-eight specimens from 209 patients at two pediatric centers and 328 specimens from 109 adults were tested. Plates were inoculated, incubated, and read for quality and quantity of growth at 24, 48, and 72 h. Five (1.5%) specimens from 4 (1.9%) children and 75 (22.9%) specimens from 16 (14.7%) adults grew B. cepacia complex. At 24, 48, and 72 h, BCSA achieved 43, 93, and 100% detection, respectively; OFPBL achieved 26, 84, and 96%, respectively; and PCA achieved 33, 74, and 84% detection, respectively. Quality was assessed as pinpoint or good growth. At 24 h, most cultures growing B. cepacia complex had pinpoint colonies. By 48 and 72 h, 48 and 69% of B. cepacia complex cultures, respectively, had good growth on BCSA, while on OFPBL 19 and 30%, respectively, had good growth and on PCA 11 and 18%, respectively, had good growth. BCSA was superior to OFPBL and PCA in suppressing organisms other than B. cepacia complex; 40 non-B. cepacia complex organisms were isolated from BCSA, 263 were isolated from OFPBL, and 116 were isolated from PCA. We conclude that BCSA is superior to OFPBL and PCA in its ability to support the growth of B. cepacia complex and to suppress other respiratory organisms.

Adult↗
PubMed1999

Evaluation of cation-exchange HPLC compared with isoelectric focusing for neonatal hemoglobinopathy screening.

BACKGROUND: Central Middlesex Hospital, in northwest London, has screened neonates for hemoglobinopathies, using the established manual technique of isoelectric focusing (IEF) since 1989. Recently, this laboratory has faced a large increase in the number of samples tested per year. This study compared the detection of hemoglobin abnormalities between the existing manual IEF method and that of automated cation-exchange HPLC to determine the reliability of HPLC and whether an automated system would save time in the laboratory. METHODS: Over a 15-month period, 25 750 blood samples, collected by heel prick onto filter paper, were tested using HPLC, and the results were compared with those obtained with IEF. RESULTS: HPLC and IEF each identified 568 patients with FAS, 151 with FAC, 49 with FAD-Punjab, 23 with FS, 3 with FC, 6 with FSC, 5 with FE, and 1 with FD. IEF detected 62 patients with FAE, whereas HPLC detected 63. This additional FAE was observed on repeat IEF. One additional heterozygote detected by HPLC was initially not observed by IEF, but was detected on repeat IEF. HPLC detected all but six cases of Hb Barts observed by IEF. One double heterozygote and four heterozygotes were detected by IEF, but not by HPLC. The detection of hemoglobin variants expressed at low concentrations was comparable for the two methods, and carryover was not observed in routine analysis on HPLC. CONCLUSIONS: HPLC is a sensitive, efficient, and time-saving alternative to IEF for the neonatal screening of common hemoglobinopathies.

Chromatography, High Pressure Liquid↗
PubMed1998

Construction of human chromosome 16- and 5-specific circular YAC/BAC libraries by in vivo recombination in yeast (TAR cloning).

Transformation-associated recombination (TAR) in yeast was exploited for the selective isolation of human DNAs as large circular yeast artificial chromosomes (YACs) from two rodent/human hybrid cell lines containing human chromosomes 5 and 16. TAR cloning vectors containing the F-factor origin of replication were constructed for use in these experiments. Presence of the F-factor origin in TAR vectors provides the capability of transferring the YACs generated by in vivo recombination in yeast into Escherichia coli cells and propagating them as bacterial artificial chromosomes (BACs). A high enrichment of human versus rodent YACs was observed during isolation of human DNA from the rodent/human hybrid cell lines. Although <3% of the DNA content in the hybrid cells was human, as many as 75% of the transformants contained human YACs. In contrast to the standard YAC cloning method based on in vitro ligation, no human/mouse chimeras were observed during TAR cloning. The constructed human chromosome 16 YAC library had approximately 2.6x coverage, represented by 4320 YAC clones with an average insert size of 80 kb. YAC clones generated from chromosome 16 were successfully converted into BACs by electroporation of DNA isolated from yeast transformants into E. coli. The BAC clones represent approximately 0.6x chromosomal coverage. Pilot YAC and BAC libraries of chromosome 5 have been also constructed. The chromosomal distribution of YAC/BACs from chromosome 5 and chromosome 16 was evaluated by fluorescence in situ hybridization (FISH). The distribution of FISH signals appeared random along the length of each chromosome. We conclude that TAR cloning provides an efficient means for generating representative chromosome-specific YAC/BAC libraries.

Animals↗
PubMed1998

Protective effects of free radical inhibitors in intracerebral hemorrhage in rat.

Iron compounds formed in the degradation of a hematoma can accelerate the formation of free radicals in adjacent ischemic or hypoperfused tissue. The purpose of this study was to examine the efficacy of compounds that quench free radicals in improving the outcome in rats with experimental intracerebral hemorrhage. Intracerebral hemorrhage was induced in rats by injection of bacterial collagenase and heparin into the caudate nucleus. Rats were treated with alpha-tocopherol plus ascorbic acid starting before hemorrhage, or with dimethylthiourea or alpha-phenyl-N-tert-butyl nitrone starting 2 h after hemorrhage, with treatment continued for 10 days after induction of hemorrhage. Outcome was assessed by behavioral analyses, magnetic resonance imaging, and histopathology. A trend towards behavioral improvement was found for rats treated with alpha-tocopherol/ascorbic acid, while behavior was significantly improved following intracerebral hemorrhage in rats treated with dimethylthiourea or alpha-phenyl-N-tert-butyl nitrone. These results suggest that free radicals may play a role in the development of brain injury following intracerebral hemorrhage, and that compounds that interrupt the free radical cascade may improve outcome. However, treatment did not significantly affect edema, resolution of the hematoma, or neuronal injury in tissue adjacent to the hemorrhage.

Animals↗
PubMed1998

Index-busting.

Explore the source record for details and available documents.

Humans↗
PubMed1998

A study of the performance of a pressure reducing foam mattress after three years of use.

This paper details the follow up clinical evaluation of a pressure reducing foam mattress (PRFM) three years after a randomised controlled trial. The PRFMs involved in the 1993 randomised controlled trial were used constantly for three years and recalled in 1996. In the original trial the control group had consisted of 18 standard NHS mattresses. In 1996 none of these mattresses were still in use which made it impossible to replicate the 1993 randomised controlled trial. Instead a clinical evaluation using the 1993 methods was carried out using the PRFMs only. Recruitment to the evaluation proved difficult because changes in clinical practice between the two studies had resulted in shorter lengths of stay in hospital for the target population. Comparison of the two outcome measures namely pressure sore incidence and the subjects' perception of comfort showed no statistically significant change between 1993 and 1996. With the exception of two damaged mattress covers all of the original foam components and covers remained in working order in 1996. During the time between the two studies, a pressure sore prevention programme was implemented within the research area. This programme has resulted in a year by year drop in the Directorate incidence rate. It is therefore not possible to attribute the low pressure sore incidence rate to the PRFMs alone. The results obtained suggest that the PRFMs appear to be providing a similar level of performance after three years of use.

Aged↗
PubMed1998

Analysis of the isopentenyl diphosphate isomerase gene family from Arabidopsis thaliana.

Two Arabidopsis thaliana cDNAs (IPP1 and IPP2) encoding isopentenyl diphosphate isomerase (IPP isomerase) were isolated by complementation of an IPP isomerase mutant strain of Saccharomyces cerevisiae. Both cDNAs encode enzymes with an amino terminus that may function as a transit peptide for localization in plastids. At least 31 amino acids from the amino terminus of the IPP1 protein and 56 amino acids from the amino terminus of the IPP2 protein are not essential for enzymatic activity. Genomic DNA blot analysis confirmed that IPP1 and IPP2 are derived from a small gene family in A. thaliana. Based on northern analysis expression of both cDNAs occurs predominantly in roots of mature A. thaliana plants grown to the pre-flowering stage.

Amino Acid Sequence↗
PubMed1998

Safety and efficacy of azithromycin in the treatment of community-acquired pneumonia in children.

OBJECTIVE: To compare the safety and efficacy of azithromycin with amoxicillin/clavulanate or erythromycin for the treatment of community-acquired pneumonia, including atypical pneumonia caused by Mycoplasma pneumoniae and Chlamydia pneumoniae. METHODS: Multicenter, parallel group, double blind trial in which patients 6 months to 16 years of age with community-acquired pneumonia were randomized 2:1 to receive either azithromycin for 5 days or conventional therapy for 10 days (amoxicillin/clavulanate if < or =5 years of age or erythromycin estolate if >5 years of age). Patients from 23 geographically diverse sites were evaluated for clinical outcomes and/or adverse events at Days 3 to 5, Days 15 to 19 and 4 to 6 weeks posttherapy. Microbiology (culture or polymerase chain reaction) was done at baseline and Days 15 to 19 for bacteria, Chlamydia pneumoniae and Mycoplasma pneumoniae. Serology for C. pneumoniae and M. pneumoniae was done at baseline and 4 to 6 weeks posttherapy. RESULTS: Of 456 patients enrolled during 17 consecutive months, 420 were evaluable. Clinical success at Study Days 15 to 19 was 94.6% in the azithromycin group and 96.2% in the comparative treatment group (P = 0.735) and at 4 to 6 weeks posttherapy 90.6 and 87.1%, respectively (P = 0.330). Evidence of infection was identified in 46% of 420 evaluable patients (1.9% bacteria, 29.5% M. pneumoniae and 15% C. pneumoniae). Microbiologic eradication was 81% for C. pneumoniae and 100% for M. pneumoniae in the azithromycin group vs. 100 and 57%, respectively, in the comparator group. Treatment-related adverse events occurred in 11.3% of the azithromycin group and 31% in the comparator group (P < 0.05). CONCLUSION: Azithromycin used once daily for 5 days produced a satisfactory therapeutic outcome similar to those of amoxicillin/clavulanate or erythromycin given three times a day for 10 days for treatment of community-acquired pneumonia. Azithromycin had significantly fewer side effects than comparator drugs.

Adolescent↗
PubMed1998

Psychological stress and burnout in medical students: a five-year prospective longitudinal study.

The aim of this study was to assess psychological morbidity and symptoms of burnout in medical students during their undergraduate training, and to identify baseline factors that predict psychological morbidity in students in the final year of the course. It was a 5-year prospective longitudinal cohort study. Students were assessed in years 1, 4 and 5 of their medical undergraduate training by means of the GHQ-12 and the Maslach Burnout Inventory. 172 (84.3%), 157 (77.0%) and 155 (75.9%) students out of an original group of 204 completed assessments in years 1, 4 and 5, respectively. 18 students were above threshold on the GHQ-12 on all three occasions, 25 on two occasions and 43 on one occasion; 69 students were never a 'case'. Students who were cases on two or more occasions were more likely to find the medical course stressful during the first year, but not subsequent years. There was no significant difference between the percentages of men and women who scored as cases on the GHQ-12 in any of the years. The best predictor of psychological morbidity in the final year of the course was the GHQ-12 score in year 1. This study suggests that a small group of students repeatedly experience psychological distress during their medical training.

Alcohol Drinking↗
PubMed1998

Comparison of PRA-STAT, sHLA-EIA, and anti-human globulin-panel reactive antibody to identify alloreactivity in pretransplantation sera of heart transplant recipients: correlation to rejection and posttransplantation coronary artery disease.

BACKGROUND: Screening pretransplantation recipient sera for percent panel reactive antibodies (%PRA) by an anti-human globulin (AHG) assay may identify recipients who are at risk for graft rejection or development of posttransplantation coronary artery disease. However, the pretransplantation AHG-%PRA does not always correlate with the occurrence of graft rejection or coronary artery disease. METHODS: We compared the predictive capacity of the AHG-%PRA with that of an enzyme-linked immunoassay (EIA)-based PRA assay that identifies immunoglobulin G bound to soluble human leukocyte antigen (sHLA) class I molecules from pooled platelets of 240 random donors (sHLA-EIA), and that of an EIA-based assay that detects immunoglobulin G anti-HLA class I antibodies bound to sHLA derived from individual HLA-typed cell cultures (PRA-STAT). The pretransplantation sera from 130 cardiac allograft recipients were comparatively tested and results evaluated. RESULTS: Although AHG-%PRA- and sHLA-EIA-determined PRA results were comparable, neither assay discriminated potential recipients at risk for rejection or coronary artery disease. However, cardiac allograft recipients with pretransplantation PRA-STAT sera > 10% were at risk for (1) graft rejection (77% vs 56%, p < .05); (2) more rejections/recipient (1.9 vs 1.0, p < .02); (3) graft rejection within 30 days (92% vs 38%, p < .001); or (4) development of coronary artery disease (48% vs 23%, p < .05) than recipients with pretransplantation PRA-STAT sera < 10%. CONCLUSIONS: PRA-STAT analysis of pretransplantation sera from potential cardiac allograft recipients may be more clinically informative about HLA alloimmunity and a better predictor of adverse clinical events than either AHG-%PRA- or sHLA-EIA-determined PRA.

Antibody Specificity↗
PubMed1997

Vitamin D receptor: no evidence for allele-specific mRNA stability in cells which are heterozygous for the Taq I restriction enzyme polymorphism.

Allelic variations of the vitamin D receptor (VDR) gene have been associated with the risk of developing prostate cancer in men and osteoporosis in postmenopausal women. Three RFLPs (TaqI, ApaI, BsmI) define two common haplotypes: BAt and baT. None of these polymorphisms change the translated protein. Since sequence variations in the 3' UTR of VDR have been linked to the different haplotypes, investigators have proposed that the stability of VDR mRNA is influenced by allelic variations. Indirect evidence suggested that allele T is less stable than allele t. In this study, we used a RT-PCR based approach to compare the stability of the big T and small t allele in normal heterozygous lymphocytes and the heterozygous cell lines NB4 (myeloid leukemia) and PC-3 and DU 145 (prostate cancers). In all three cases, we did not find a significant difference in stability. Interestingly, we consistently observed 30% less RT-PCR product derived from the small t allele mRNA in steady state, a finding which also speaks against a higher stability of the small t allele mRNA. These results indicate a variation in transcriptional regulation rather than mRNA stability between the alleles. We hypothesize that an unknown gene or genes in linkage with the polymorphisms is (are) responsible for the relationship between risk of prostate cancer and VDR polymorphisms.

Alleles↗
PubMed1997

Quantitation of the inhibition of Hfr x F- recombination by the mutagenesis complex UmuD'C.

The UmuD'C complex and RecA protein are two essential components in mutagenic repair of gaps produced by the replication of damaged DNA. In this process, the UmuD'C complex might help DNA polymerase to synthesize DNA across a lesion. Besides, a RecA polymer wrapping around single-stranded DNA could function as a directional chaperone to target the UmuD'C complex at the lesion. It was shown in our laboratory that the UmuD'C complex prevents homologous recombination and recombinational repair when expressed at elevated levels. To find out whether the UmuD'C complex inhibits recombination by interfering directly with RecA, we measured the kinetics of inhibition of Hfr x F- recombination in F- recipients in which either RecA or UmuD'C were made to vary. The cell concentrations of RecA and UmuD'C proteins were adjusted by having the recA and the umuD'C genes regulated by the arabinose P(BAD) promoter. In the absence of the UmuD'C complex, recombination was a function of RecA concentration and then reached a plateau when the RecA concentration was above 9000 monomers/cell. At a fixed RecA concentration, the yield of Hfr x F- recombinants decreased as a function of the UmuD'C cell concentration. At a given UmuD'C/RecA ratio, recombination inhibition by UmuD'C was reversed by increasing the RecA cell concentration. RecA1730, a mutant protein impaired in the chaperone activity, was insensitive to UmuD'C inhibition. We propose a model accounting for the RecA chaperone function in SOS mutagenesis and for the UmuD'C inhibitory effect on homologous recombination. We suggest that the UmuD'C complex is placed at the tip of a RecA polymer as a result of a treadmilling process. This would position the UmuD'C complex right at a lesion while the capping by UmuD'C would destabilize a RecA polymer and thereby abort the recombination process.

Bacterial Proteins↗